WOOD ANATOMY OF SCHEFFLERA AND RELATED TAXA (ARALIACEAE). II. SYSTEMATIC WOOD ANATOMY OF NEW CALEDONIAN SCHEFFLERA - Brill
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IAWA Journal, Vol. 22 (3), 2001: 301– 330
WOOD ANATOMY OF SCHEFFLERA AND RELATED TAXA
(ARALIACEAE). II. SYSTEMATIC WOOD ANATOMY OF
NEW CALEDONIAN SCHEFFLERA
by
Alexei A. Oskolski 1 & Porter P. Lowry II 2a & b
SUMMARY
The wood anatomy of 22 of the 26 species of Schefflera occurring in
New Caledonia was studied. Only two features (the presence of scalari-
form perforation plates and scanty paratracheal axial parenchyma) ap-
pear to be constant throughout the species examined. The pattern of
wood structure diversity was analyzed using PCA; the results generally
agree with the current recognition of four groups of species among New
Caledonian Schefflera based on macromorphology. Three of these
groups (Dizygotheca, “Canacoschefflera” and “Gabriellae”) represent
natural assemblages closely related to one another. The fourth group
(Schefflera sect. Schefflera) is isolated from the others, as indicated by
its very large rays and abundant septate fibres. The occurrence of crys-
tals in chambered cells of axial parenchyma was observed for the first
time in Araliaceae. The wood structure of Schefflera plerandroides,
previously placed in the segregate genus Octotheca, shows no essential
differences from that of the other members of the Dizygotheca group,
supporting the hypothesis that polymerous flowers have evolved inde-
pendently at least twice within the Schefflera alliance.
Key words: Araliaceae, Schefflera, Dizygotheca, Canacoschefflera, New
Caledonia, systematic wood anatomy, crystals, chambered cells.
INTRODUCTION
Schefflera J. R. Forst. & G. Forst. is the largest genus of Araliaceae, with an estimated
number of species ranging from 400 (Grushvitzky et al. 1985) to 650–700 (Lowry
1989), or as high as 900 (Frodin 1995), and making up more than half of the family.
Schefflera is currently circumscribed broadly (Frodin 1975, 1982, 1989, 1993; see
also Lowry 1989) to include several segregates usually recognized as synonyms (e.g.,
Agalma, Brassaia, Cephaloschefflera, Crepinella, Geopanax, Heptapleurum, Neocus-
sonia, Scheffleropsis, and Sciadophyllum), plus several others that have been main-
1) Botanical Museum, V. L. Komarov Botanical Institute of the Russian Academy of Sciences,
Prof. Popov str. 2, 197376 St. Petersburg, Russia [E-mail: oskolski@ao1818.spb.edu].
2a) Missouri Botanical Garden, P.O. Box 299, St. Louis, MO 63166-0299, U.S.A. [E-mail:
lowry@mobot.org].
2b) Laboratoire de Phanérogamie, Muséum National dʼHistoire Naturelle, 16 rue Buffon, 75005
Paris, France [E-mail: lowry@mnhn.fr].
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tained as distinct in some treatments (e.g., Didymopanax, Dizygotheca, Octotheca,
and Plerandra). This broad interpretation of Schefflera has, however, been called into
question in a recent study (Wen et al. 2001) in which molecular data suggest that the
genus, as currently defined, may be polyphyletic.
Species of Schefflera (sensu lato) occur in most tropical and subtropical regions,
with especially high concentrations in Malesia, Southeast Asia, New Caledonia, the
Andes and the Guyana Highlands. Among these areas, the small southwest Pacific
island of New Caledonia (c. 17,000 km2) is remarkable because of its high levels of
diversity and endemism, both within Schefflera (26 species) and among Araliaceae as
a whole, with a total of eight genera and over 90 native species recorded, only two of
which occur elsewhere (Lowry 1986b, 1989, unpubl. data; Lowry et al. 1986). The
New Caledonian Schefflera species, along with a few close relatives on neighboring
islands (cf. Smith 1985; Lowry 1989), also appear to be rather isolated systematically
and their relationships to other groups in the genus are somewhat obscure.
The diversity and distinctiveness of the New Caledonian flora in general, and of
its Araliaceae in particular, are due in large part to the wide variety of habitat types
present on the island, which result from the complex interactions of topography, cli-
mate, and a special set of edaphic features, including large areas of ultramafic soils
(cf. Morat 1993; Lowry 1998). This is compounded by the islandʼs long geological
history, during which it has been isolated from Australia for approximately 80 million
years (Kroenke 1996), serving as a refuge for many “primitive” vascular plants (Raven
& Axelrod 1972, 1974; Raven 1980), including representatives of some basal line-
ages of Araliaceae (Plunkett & Lowry 2001).
All 26 species of New Caledonian Schefflera are endemic to the island (Lowry,
unpubl. data). Their habit varies from small monocaulous treelets to large, well
branched trees up to 20 m in height. Species occur primarily in moist evergreen for-
ests; the genus is less well represented in sclerophyllous forests and maquis vegeta-
tion (cf. Jaffré et al. 1993; Lowry 1998). Four well-defined groups can be distin-
guished within the genus in New Caledonia based on morphological differences in
the leaves, inflorescences, flowers, and fruits, as follows:
1) Schefflera sect. Schefflera is represented by three species in New Caledonia, with
five additional members occurring in other island groups of the southwest Pacific
(one species each in Vanuatu, Samoa, and New Zealand, and two species in Fiji;
Lowry 1989). The type of the genus (S. digitata J.R. Forst. & G. Forst.) from New
Zealand belongs to this section, which could thus be interpreted as “Schefflera in
the strictest sense” (Lowry 1989). This group is distinguished by its paniculate in-
florescences bearing numerous umbellules or racemules of small flowers with 5
stamens and an equal number of carpels and free styles, and its thin, often mem-
branaceous leaves and almost succulent stems and petioles.
2) The Dizygotheca group, previously recognized as a distinct genus Dizygotheca
N.E. Brown (including Octotheca R. Vig.) by several authors (e.g., Guillaumin
1948; Hutchinson 1967), has twelve species in New Caledonia (all endemic) and
two additional representatives in Vanuatu (Lowry 1989). Members of this group
are characterized by anthers with 8 thecae (vs. 4 thecae in all other Schefflera) and
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a distinctive paniculate-umbellate inflorescence structure in which the lateral axes
usually have a median pseudo-whorl of umbellules (cf. Lowry 1989). They also
have a chromosome number of n = 24 (as compared to n = 12 for nearly all other
Schefflera examined to date) (Lowry 1986b, unpubl. data). Most Dizygotheca in
New Caledonia have free styles (united in two species), and a majority are found
on non-ultramafic substrates. Octotheca was originally described as a monotypic
genus on the basis of its polymerous flowers (Viguier 1906; see also Viguier 1909,
1925; Hutchinson 1967; Eyde & Tseng 1971; Tseng & Hoo 1982) with 10–15
carpels and 10, 15 or 20 stamens (vs. 5–10 carpels and 5 stamens in Dizygotheca),
but it otherwise shares all of the features that characterize the group, and should
probably not be retained.
3) The “Canacoschefflera” group is an informally recognized assemblage of nine en-
demic species distinguished by their once- or twice-umbellate inflorescences bear-
ing 2–5-carpellate flowers with an equal number of free or basally united styles,
and leaves that are usually quite coriaceous. Species of “Canacoschefflera” occur
primarily on ultramafic substrates at higher elevations.
4) The “Gabriellae” group is represented by two species in New Caledonia, and two
others occurring elsewhere in the southwest Pacific, S. vanuatua Lowry in Vanuatu
(Lowry 1989) and S. seemanniana A.C. Smith in Fiji (Smith 1985). Members of
this group are characterized by strictly compound umbellate inflorescences bear-
ing generally 5-merous flowers with the styles fused into a short beak, and leaflets
with numerous parallel secondary veins. The New Caledonian species are often
large trees that can play an important role in the composition of forest communi-
ties, with one (S. gabriellae Baill.) occurring primarily on ultramafic substrates
and the other (S. pancheri Baill.) found almost exclusively on other soil types.
Wood anatomy has been shown to be a useful tool for examining infrageneric rela-
tionships within both Schefflera (Oskolski 1995) and other groups of Araliaceae
(Rodriguez 1957; Oskolski 1996, 2001; Oskolski et al. 1997; Oskolski & Lowry 2000).
Oskolski (1995), using a representative sample of members of the genus from through-
out the world, recognized seven broad groups within Schefflera on the basis of their
wood structure, and proposed interpretations of their possible systematic relation-
ships. However, data on the wood anatomy of New Caledonian Schefflera were scanty,
and hence insufficient to formulate any conclusive interpretations about the position
of the four groups represented on the island. In fact, only two (or perhaps three) of
these species have been examined previously [S. gabriellae (Sarlin 1954; Oskolski
1994, 1995, 1996); S. elegantissima (Veitch ex Masters) Lowry & Frodin (Oskolski
1994, 1996 as Dizygotheca elegantissima), and Dizygotheca sp. (Record & Hess 1944;
Metcalfe & Chalk 1950)].
The present study, which is part of a general survey of wood anatomy throughout
Araliaceae (Oskolski 1994, 1995, 1996; Oskolski et al. 1997; Oskolski & Lowry 2000),
surveys the wood structure of 22 of the 26 species of Schefflera represented in New
Caledonia. The results are considered with regard to the systematic relationships among
the groups and within the genus.
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Table 1. Variables selected for the Principal Component Analysis.
Variables Coding of the character states
1 radius of wood sample (mm)
2 average vessel element length (μm)
3 average tangential diameter of vessel lumina (μm)
4 percentage of solitary vessels
5 maximal number of vessel lumina per group
6 average vessel frequency per mm 2
7 maximal bar number per perforation plate
8 level of specialization (sensu Bailey) of mostly scalariform = 0
intervessel pitting scalariform to opposite = 25
mostly opposite = 50
opposite to alternate = 75
mostly alternate = 100
9 average fibre length (μm)
10 abundance of septate fibres no septate fibres = 0
solitary [up to c. 25% of fibres septate] = 25
common [c. 25–50% of fibres septate] = 50
predominate [c. 50–75% of fibres septate] = 75
almost all the fibres septate = 100
11 maximal ray width (number of cells)
12 average ray height (mm)
13 average number of uniseriate rays per mm
14 average number of multiseriate rays per mm
15 average annual rainfall (mm)
16 substrate type non-ultrabasic = 0
intermediate = 50
ultrabasic = 100
MATERIALS AND METHODS
The wood samples studied were collected in New Caledonia by the second author in
the 1980s, and in 1997 by both authors and G.M. Plunkett (voucher specimens are
deposited at LE, MO, NOU, P, and various other institutions). Several additional sam-
ples were obtained from institutional wood collections (Uw, Lw). The specimens were
mostly taken from stems with a secondary xylem radius of more than 10 mm, although
juvenile samples were studied in a few species. A list of the samples and their stem
diameters is given in Tables 2–5.
Standard procedures for the study of wood structure were employed to prepare
sections and macerations for light microscopic studies (Carlquist 1988). Specimens
for scanning microscopy were prepared according to Exley et al. (1974, 1977). De-
scriptive terminology and measurements follow Carlquist (1988) and the IAWA List
of Microscopic Features for Hardwood Identification (IAWA Committee 1989), ex-
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cept that for the diameter of intervessel pits the vertical dimension is recorded. Esti-
mates of the average annual rainfall at the localities where the wood samples were
collected are derived from the climatological map of New Caledonia (Section dʼHydro-
logie de lʼORSTOM 1981).
Principal Components Analysis (PCA) was used in an effort to differentiate among
a) between-sample variation patterns of the wood anatomical characters examined
and b) differences correlated with the habitats in which the plants grow. A total of 16
variables were selected for the PCA (Table 1). The wood samples of S. elegantissima
[Uw UN911] and S. pancheri [Sarlin 302] were excluded from the numerical analy-
sis because no data are available on their collection localities. The program package
STATISTICA 5.0 was used to perform the PCA.
RESULTS
For the following descriptions, in cases where multiple samples of a species were
examined and a feature was seen in only a portion of the material, the corresponding
voucher collections are indicated in brackets.
Schefflera sect. Schefflera (Fig. 1– 4, 25, 29, 30; Table 2)
Material studied: Schefflera candelabra Baill.: Plateau de Dogny, Lowry 4726. – S. pseudo-
candelabra R. Vig.: Plateau de Dogny, Lowry 3215; Mé Ori, Lowry 4795. – S. vieillardii
Baill.: Mandjélia, Lowry 4747; Roches dʼOuaïème, Lowry 4786.
Diagnostic characters — Vessels narrow to moderately wide (up to 100 μm or more
in diameter), perforation plates simple and scalariform, intervessel pitting exclusively
scalariform, nearly all fibres septate, rays very high (commonly more than 2 mm) and
wide (up to 8–12 cells), with 2–6 (up to 8) rows of upright and square marginal cells,
multiseriate portions of rays distinctly wider than uniseriate ones, crystals not ob-
served.
Growth rings absent or indistinct, marked by tangential zones of thin-walled fibres.
Vessels angular, rarely rounded in outline, rather small (tangential diameter usu-
ally less than 80 μm, up to 112 μm in S. pseudocandelabra [4795]). Vessel frequency
from 20 per mm2 in S. pseudocandelabra [4795] to 54 per mm2 in S. candelabra.
Vessels solitary or in radial multiples of 2–4 (up to 8 in S. candelabra). Vessel walls
3–6 μm thick. Tyloses not observed. Vessel element length (560–)870–1030(–1280)
μm. Perforation plates simple and scalariform with few to numerous bars (up to 47),
in highly or less oblique end walls. Intervessel pits exclusively scalariform, 4–7 μm
in vertical size, with rounded margins and slit-like apertures. Vessel-ray and vessel-
axial parenchyma pits half-bordered or with indistinct borders, similar to intervessel
pits in size and shape. Helical thickenings absent.
Vasicentric and vascular tracheids not observed.
Fibres libriform, very thin- to thin-walled (fibre walls 2–6 μm thick), septate, with
simple to minutely bordered pits with slit-like apertures in radial and tangential walls.
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Table 2. Wood anatomical features of the species of Schefflera sect. Schefflera.
1: Annual rainfall (mm) — 2: Type of substrate (+ = ultrabasic; ± = intermediate; – = non-ultrabasic) — 3: Radius of wood sample (mm) — 4: Aver-
age length of vessel elements (μm) — 5: Tangential diameter of vessels (average / maximum, μm) — 6: Percentage of solitary vessels / the greatest
number of vessels in a vessel group — 7: Vessel frequency (per sq. mm) — 8: Usual / min.-max. number of bars per perforation plate — 9: Average
length of libriform fibres (μm) — 10: Width of multiseriate rays (average / maximum, cells) — 11: Height of multiseriate rays (average / maximum,
mm) — 12: Number of multiseriate rays per mm — 13: Number of uniseriate rays per mm — 14: Scores of Factor 1 — 15: Scores of Factor 2 —
16: Scores of Factor 3.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
S. candelabra
(Lowry 4726) 1700 – 12 873 61 / 88 16/8 54 0/0-44 1072 6.6/10 2.3/8.1 3.8 0.1 -0.67 -2.60 0.91
S. pseudocandelabra
(Lowry 3215) 1700 + 12 942 58 / 74 19/6 52 0/0-47 1045 5.4/8 1.3/3.2 3.5 0.2 -0.49 -1.87 0.90
S. pseudocandelabra
(Lowry 4795) 1500 ± 23 1032 82/112 23/5 20 0/0-38 1432 7.4/12 2.2/4.0 2.7 0.2 -2.24 -2.20 0.57
S. vieillardii
(Lowry 4747) 2000 – 22 1014 75/108 20/6 24 0/0-18 1260 6.9/10 2.7/6.1 2.8 0.1 -1.64 -1.85 0.54
S. vieillardii
(Lowry 4786) 2500 – 15 958 67/92 17/6 39 0/0-26 1185 5.1/8 3.8/10.4 3.7 0.3 -1.12 -2.31 0.70
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Legends on page 308.
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Axial parenchyma scanty paratracheal. Strands composed of 8–14 cells. Helical
thickenings rarely present on inner walls of several axial parenchyma cells in S. can-
delabra [4726] (Fig. 4). Rays 2– 4 per mm, uni- and multiseriate, mostly 3–8 cells
in width (up to 12 in S. pseudocandelabra [4795]). Rays very high, commonly more
than 2 mm (up to 10.4 mm in S. vieillardii [4786]). Multiseriate rays composed of
procumbent body cells, and upright and square cells forming complete sheaths and
2–6 (up to 8) marginal rows (Kribsʼ type Heterogeneous I). Uniseriate rays composed
of upright and square cells. Radial canals small (20–30 μm in diameter), bordered by
few rather large thin-walled epthelial cells (Fig. 2). Crystals not observed.
The Dizygotheca group (Fig. 5–10, 22, 30, 35, 36; Table 3)
Material studied: Schefflera baillonii (R. Vig.) Lowry, ined.: Roches dʼOuaïème, Lowry 4782.
– S. elegantissima (Veitch ex Masters) Lowry & Frodin: sine loc., Cantonpark 74-713, Uw
UN911; Mt. Mou, Lowry 3801, 4715. – S. moratiana Lowry, ined.: Ponandou River valley,
Lowry 4762, 4767. – S. nono Baill.: Plateau de Dogny, Lowry 4731. – S. osyana (Hort.)
Lowry & Frodin, ined.: Plateau de Dogny, Lowry 4734. – S. plerandroides (R. Vig.) Lowry,
ined.: Mandjélia, Lowry 4748, 4751; Roches dʼOuaïème, Lowry 4777, 4780. – S. polydactylis
(Montrousier) Lowry, ined.: Mt. Poum, Lowry 3327; Mt. Taom, Lowry 3790. – S. reginae
(Hort. Linden ex André) Lowry, ined.: Mt. des Sources, Lowry 3766; Mt. Dzumac, Lowry
4651, 4660; Mt. Humboldt, Plunkett 1483. – S. toto Baill.: Plateau de Dogny, Lowry 4727. –
S. veitchii (Hort. ex Carrière) Frodin & Lowry: Baie Tina, Lowry 3390, 4665. – Schefflera sp.:
New Caledonia, Pouembout, Lowry 4737.
Diagnostic characters — Vessels narrow (less than 90 μm in diameter), perforation
plates almost exclusively scalariform, intervessel pitting mostly scalariform to oppo-
site, septate fibres solitary to common, multiseriate rays with 1– 4 (up to 10) rows of
upright and square marginal cells, rays 6–10 per mm, multiseriate portions of rays
relatively narrow (often twice as wide as their uniseriate portions), ray height com-
monly exceeding 0.8 mm, crystals present in upright and square ray cells in some
species.
←
Fig. 1– 4. Species of Schefflera sect. Schefflera. — 1 & 2: Schefflera vieillardii (Lowry 4747);
1: TS, growth rings absent; 2: TLS, scalariform intervessel pitting, numerous septate fibres,
large heterogeneous rays with small radial canals (arrows). – 3 & 4: S. candelabra (Lowry
4726); 3: TS, growth ring boundaries indistinctly marked by zones of thin-walled fibres;
4: TLS, axial parenchyma cells bearing helical thickenings on cell walls (arrows). — Scale
bars = 100 μm; magnification of Fig. 1 & 2 as in Fig. 3.
→
Fig. 5–8. Species of the Dizygotheca group. — 5 & 6: Schefflera reginae (Lowry 3766); 5: TS,
growth rings absent; 6: TLS, multiseriate portions of heterogeneous rays up to twice as wide
as their uniseriate portions. – 7 & 8: S. veitchii (Lowry 4665); 7: TS, growth ring boundary
in-distinctly marked by the vessel arrangement; 8: TLS, multiseriate portions of heterogeneous
rays distinctly wider than uniseriate ones, radial canal, prismatic crystals in marginal ray cells
(arrows). — Scale bar = 100 μm; magnification of Fig. 5–7 as in Fig. 8.
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310
1: Annual rainfall (mm) — 2: Type of substrate (+ = ultrabasic; ± = intermediate; – = non-ultrabasic) — 3: Radius of wood sample (mm) — 4: Aver-
age length of vessel elements (μm) — 5: Tangential diameter of vessels (average / maximum, μm) — 6: Percentage of solitary vessels / the greatest
number of vessels in a vessel group — 7: Vessel frequency (per sq. mm) — 8: Usual / min.-max. number of bars per perforation plate — 9: Average
length of libriform fibres (μm) — 10: Width of multiseriate rays (average / maximum, cells) — 11: Height of multiseriate rays (average / maximum,
mm) — 12: Number of multiseriate rays per mm — 13: Number of uniseriate rays per mm — 14: Scores of Factor 1 — 15: Scores of Factor 2 —
16: Scores of Factor 3.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
S. baillonii
(Lowry 4782) 2500 – 22 898 48/64 16/6 49 9/2-23 1053 2.5/4 0.6/1.3 4.0 2.1 0.52 -0.19 -0.27
S. elegantissima
(Uw UN911) 18 1119 60/77 13/8 56 4/1-33 1389 2.9/4 0.6/1.3 6.2 1.4
S. elegantissima
(Lowry 3801) 1700 + 28 798 62/81 36/5 49 5/2-20 1012 2.3/3 0.5/1.2 6.0 0.8 0.27 0.15 -1.08
S. elegantissima
(Lowry 4715) 1700 – >50 864 55/88 41/5 35 5/1-19 1259 2.8/4 0.5/0.8 5.6 0.9 -0.65 0.22 -2.33
S. moratiana
(Lowry 4762) 3000 – 29 1061 47/60 26/8 51 10/2-24 1230 4.4/6 0.8/1.6 4.3 1.5 -0.12 -0.38 -0.30
S. moratiana
(Lowry 4767) 3000 – 18 992 54/72 13/8 51 17/4-28 1194 2.2/3 0.5/0.8 3.6 2.5 0.27 -0.33 0.27
S. nono
(Lowry 4731) 1700 – 22 932 44/68 36/7 54 9/1-30 1063 3.2/5 0.6/0.8 3.4 2.7 0.47 -0.47 -0.91
S. osyana
(Lowry 4734) 1700 – 27 1151 68/88 24/5 38 4/1-27 1391 3.6/5 0.7/1.0 4.6 1.4 -1.04 -0.38 -0.55
S. plerandroides
(Lowry 4748) 2000 – 29 684 53/80 48/5 36 5/2-22 843 2.9/4 0.5/0.8 4.5 2.0 0.72 -0.11 -2.13
S. plerandroides
(Lowry 4751) 2000 – 16 922 46/60 21/10 77 3/1-32 1007 3.4/5 0.4/0.6 5.3 2.8 1.07 -0.68 -0.04
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
S. plerandroides
(Lowry 4777) 2500 – 39 860 46/64 36/5 49 4/1-22 1082 2.4/4 0.5/1.0 4.5 2.5 0.46 -0.06 -1.61
S. plerandroides
(Lowry 4780) 2500 – 19 914 45/64 31/5 37 5/0-20 1160 2.6/4 0.6/0.8 3.7 2.0 0.27 -0.11 -0.98
S. polydactylis
(Lowry 3327) 1500 + 11 767 48/74 20/6 50 6/2-19 1047 2.9/4 0.6/1.5 5.2 2.2 1.00 0.10 -0.20
S. polydactylis
(Lowry 3790) 1500 + 11 833 41/56 8/12 80 7/3-18 909 2.8/4 0.6/1.1 4.7 2.0 1.51 -0.09 1.30
S. reginae
(Lowry 3766) 4000 + 21 1029 39/53 29/6 70 5/1-14 1168 2.7/4 0.5/0.8 5.2 1.5 0.69 0.22 -0.21
S. reginae
(Lowry 4651) 1700 + 16 784 42/60 25/8 70 4/1-23 969 2.2/3 0.6/0.9 5.8 3.3 1.55 -0.15 -0.32
S. reginae
Oskolski & Lowry II — Wood anatomy of Schefflera
(Lowry 4660) 1700 + 19 783 44/56 17/7 71 7/2-20 978 4.9/8 0.5/0.9 4.3 2.9 1.14 -0.22 0.30
S. reginae
(Plunkett 1483) 4000 16 788 48/68 44/7 49 2/2-23 1053 2.6/4 0.5/0.8 4.0 1.8 0.73 0.15 -0.76
S. toto
(Lowry 4727) 1700 – 33 879 50/68 20/8 58 5/1-23 1117 3.7/5 0.7/1.3 5.4 4.2 0.83 -0.43 -0.71
S. veitchii
(Lowry 3390) 1000 – 8 849 51/74 11/10 83 18/3-24 1016 3.5/6 0.6/0.9 8.1 2.1 1.28 -1.02 0.13
S. veitchii
(Lowry 4665) 1000 – 15 749 51/68 18/10 63 5/2-24 959 3.5/5 0.4/0.7 6.4 0.8 0.93 -0.58 -0.15
Schefflera sp.
(Lowry 4737) 1000 – 16 905 42/64 34/6 56 17/5-38 1226 3.4/5 0.8/1.5 8.1 2.2 0.57 -1.17 -1.54
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Growth rings absent or indistinctly marked by tangential zones of thin-walled fibres
mixed with solitary strands of marginal parenchyma (S. moratiana [4767], S. nono, S.
reginae [Plunkett 1483]), and also by zones of more numerous vessels (S. veitchii
[4665]), or by lines of marginal parenchyma (S. polydactylis [3790], S. veitchii [3390]).
Vessels rounded, rarely angular in outline, rather small (tangential diameter < 90
μm). Vessel frequency from 35 per mm2 in S. elegantissima [4715] to 83 per mm2 in
S. veitchii [3390]. Vessels solitary and in radial multiples of 2–5 (up to 12 in S. poly-
dactylis [3790]). Vessel walls 2–5 μm thick. Tyloses present in S. elegantissima [3801],
S. osyana [4734], S. moratiana [4762], S. polydactylis [3790], S. reginae, S. veitchii
[4665] and S. toto [4727], but not observed in other samples. Vessel element length
(380–)680–1150(–1650) μm. Perforation plates scalariform with few to numerous
bars (up to 38 in Schefflera sp. [4737]), reticulate, sometimes simple (in S. pler-
androides [4780] only) in more or less oblique end walls. Intervessel pits scalariform
to opposite (mostly opposite in S. elegantissima and S. osyana), sometimes alternate,
6–8(–9) μm in vertical diameter, with rounded margins and slit-like apertures. Ves-
sel-ray and vessel-axial parenchyma pits simple or half-bordered with small borders,
similar to intervessel pits in size and shape. Helical thickenings absent.
Vasicentric and vascular tracheids not observed.
Fibres libriform, mostly thick-walled (fibre walls 3–6(–8) μm) and occasionally
thin-walled (especially in S. elegantissima), mostly non-septate (septate fibres rela-
tively numerous in S. elegantissima, S. moratiana [4767], S. osyana, and few in other
species, not observed in S. polydactylis [3327] and S. reginae [4660], located mostly
in immediate vicinity of rays), with few simple to minutely bordered pits (large, dis-
tinctly bordered pits > 5 μm in diameter in S. reginae [3766] and S. toto [4727]), with
slit-like apertures in radial walls.
Axial parenchyma scanty paratracheal and marginal (forming continuous tangen-
tial lines in S. veitchii [3390], interrupted lines in S. polydactylis [3790], S. moratiana
[4767], S. nono and S. reginae [Plunkett 1483]). Strands composed of (3–)4–6(–8)
cells.
Rays 6–10 per mm, uni- and multiseriate of 2– 4 cells in width (up to 6 in S. morati-
ana [4762] and S. veitchii [4665], and to 8 in S. reginae [4660]). Ray height com-
monly less than 1 mm, but > 1 mm in S. elegantissima [3801; UN911], S. polydactylis,
S. osyana [4734], S. toto [4727] and Schefflera sp. [4737], up to 1.5 mm high in S.
moratiana [4762]. Multiseriate rays composed mostly of procumbent body cells (mixed
occasionally with square and upright cells) and 1–4 (up to 10) marginal rows of square
and upright cells (Kribsʼ type Heterogeneous I); solitary sheath cells rarely present.
Multiseriate portions of rays usually a little wider than (up to twice as wide as) the
uniseriate portions (except in S. elegantissima [4715], S. osyana [4734], S. moratiana
[4762], S. plerandroides [4751], S. veitchii [4665], and Schefflera sp. [4737], with
multiseriate portions of rays usually distinctly wider than uniseriate ones). Uniseriate
rays composed mostly of square and upright cells. Radial canals present in S. poly-
dactylis [3327] and S. veitchii, rather wide (30–50 μm in diameter), bordered by
numerous small, thin-walled epithelial cells. Prismatic calcium oxalate crystals in
upright and square cells of both multiseriate and uniseriate rays in S. elegantissima,
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S. osyana [4734], S. moratiana [4762], S. polydactylis [3790], S. veitchii, S. toto [4727],
and Schefflera sp. [4737]. Crystal-containing cells evenly distributed among other
ray cells.
Note — The wood sample described by Oskolski (1994, 1995, 1996) under the name
S. nono (SFCw s.n.) was undoubtedly misidentified. As no accompanying voucher
specimen has been located, we cannot verify its identity, but it probably belongs to a
species of Polyscias.
The “Canacoschefflera” group (Fig. 11–16, 21, 23, 26–28, 32–34; Table 4)
Material studied: Schefflera crassipes Baill.: Mt. Mou, Lowry 4701; Mé Ori, Lowry 4797. –
S. elongata Baill.: Mt. Dzumac, Lowry 3353, 4659. – S. emiliana Baill.: Mt. Humboldt, Plunkett
1486a (coll. Suprin). – S. gordonii Lowry, ined.: Col de Yaté, Lowry 4674. – S. neocaledonica
Lowry, ined.: Mt. Dzumac, Lowry 4656. – S. pachyphylla Harms: Upper Ouinné River Basin,
Lowry 3691. – S. taomensis Lowry, ined.: Mt. Taom, Lowry 3769; Kopéto Massif, Lowry
4742. – S. veillonorum Lowry, ined.: Roches dʼOuaïème, Lowry 3917, 4774, 4784.
Diagnostic characters — Vessels narrow (diameter commonly less than 90 μm), per-
foration plates scalariform and simple, intervessel pitting mostly opposite to alter-
nate, septate fibres solitary or absent, rays less than 6 per mm, height less than 0.7
mm, multiseriate rays composed of procumbent body cells or also of square and up-
right cells forming 1–2 (up to 4) marginal rows, crystals present in chambered cells of
diffuse axial parenchyma in some species.
Growth rings absent (S. pachyphylla) or indistinctly marked by tangential zones of
thin-walled fibres (S. crassipes [4742]), by bands of thick-walled fibres (S. gordonii),
or by interrupted lines of marginal parenchyma (S. elongata [3353]).
Vessels rounded, rarely angular in outline, rather small (tangential diameter usu-
ally < 80 μm except in S. veillonorum [4784] up to 104 μm). Vessel frequency from
22 per mm2 in S. veillonorum [4774] to 72 per mm2 in S. taomensis (and to 142 per
mm2 in juvenile wood of S. emiliana). Vessels solitary and in radial multiples of 2–5
→
Fig. 9–12. Species of the Dizygotheca and “Canacoschefflera” groups. — 9 & 10: Schefflera
moratiana (Lowry 4767); 9: TS, growth ring boundaries (arrows) indistinctly marked by zones
of thin-walled fibres mixed with solitary strands of marginal parenchyma; 10: TLS, solitary
septate fibres (arrow), multiseriate portions of heterogeneous rays up to twice as wide as their
uniseriate portions. – 11 & 12: S. elongata (Lowry 4659); 11: TS, growth rings absent, soli-
tary strands of diffuse axial parenchyma (arrows); 12: TLS, prismatic crystals in axial paren-
chyma cells, homogeneous rays. — Scale bar = 100 μm; magnification of Fig. 9, 10 & 12 as
in Fig. 11.
→→
Fig. 13–16. Species of the “Canacoschefflera” group. — 13 & 14: Schefflera veillonorum
(Lowry 4774); 13: TS, growth rings absent, no diffuse axial parenchyma; 14: TLS, homogene-
ous rays. – 15 & 16: S. crassipes (Lowry 4742); 15: TS, growth ring boundary (arrow) indis-
tinctly marked by zone of thin-walled fibres; 16: TLS, heterogeneous rays with 1 or 2 marginal
rows of square and upright cells. — Scale bar = 100 μm; magnification of Fig. 13, 14 & 16 as
in Fig. 15.
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Legends on page 313.
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Legends on page 313.
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via free accessTable 4. Wood anatomical features of “Canacoschefflera” species.
316
1: Annual rainfall (mm) — 2: Type of substrate (+ = ultrabasic; ± = intermediate; – = non-ultrabasic) — 3: Radius of wood sample (mm) — 4: Aver-
age length of vessel elements (μm) — 5: Tangential diameter of vessels (average / maximum, μm) — 6: Percentage of solitary vessels / the greatest
number of vessels in a vessel group — 7: Vessel frequency (per sq. mm) — 8: Usual / min.-max. number of bars per perforation plate — 9: Average
length of libriform fibres (μm) — 10: Width of multiseriate rays (average / maximum, cells) — 11: Height of multiseriate rays (average / maximum,
mm) — 12: Number of multiseriate rays per mm — 13: Number of uniseriate rays per mm — 14: Scores of Factor 1 — 15: Scores of Factor 2 —
16: Scores of Factor 3.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
S. crassipes
(Lowry 4701) 1700 + 23 850 66/92 21/10 32 6/0-24 1035 2.5/4 0.3/0.5 3.7 2.0 0.17 0.46 0.34
S. crassipes
(Lowry 4797) 1500 + 27 906 64/84 27/7 31 4/2-18 1126 2.7/4 0.3/0.5 3.2 0.8 -0.33 1.02 -0.13
S. elongata
(Lowry 3353) 1700 + 19 738 55/77 12/6 32 1/0-17 1044 2.8/4 0.3/0.5 3.4 1.1 0.27 0.73 0.36
S. elongata
(Lowry 4659) 1700 + 20 920 57/72 10/11 39 1/0-27 1167 2.2/4 0.2/0.4 3.5 1.2 -0.03 0.58 1.12
S. emiliana
(Plunkett 1486a) 4000 10 722 40/60 7/17 108 5/0-18 882 2.7/5 0.5/0.9 2.9 2.8 2.05 0.21 2.36
S. gordonii
(Lowry 4674) 3000 + 27 857 53/68 11/7 34 5/0-22 1276 2.3/3 0.3/0.5 1.5 1.0 -0.22 0.81 0.77
S. neocaledonica
(Lowry 4656) 1700 + 29 921 59/84 6/9 35 3/0-19 980 2.2/3 0.2/0.4 2.9 1.7 0.22 1.18 0.88
S. pachyphylla
(Lowry 3691) 3000 + 19 847 51/71 15/7 32 2/0-11 930 2.8/4 0.4/0.7 2.0 0.5 0.32 1.05 0.68
S. taomensis
(Lowry 3769) 1300 + 12 938 52/71 19/8 72 5/0-22 1015 2.1/3 0.3/0.6 3.0 1.1 0.57 0.36 0.73
S. taomensis
(Lowry 4742) 1500 + 24 1080 59/80 17/19 41 4/1-30 1220 2.2/3 0.4/0.5 2.1 0.9 -0.37 0.78 1.98
S. veillonorum
(Lowry 3917) 2500 – 17 884 48/71 20/7 27 5/0-21 979 3.0/4 0.3/0.5 2.8 0.9 0.21 0.96 0.33
S. veillonorum
(Lowry 4774) 2500 – 23 909 53/72 21/6 22 4/0-20 1142 2.6/4 0.3/0.5 2.2 0.4 -0.35 1.09 0.23
S. veillonorum
(Lowry 4784) 2500 – 27 802 72/104 30/5 26 6/0-17 1000 3.3/5 0.3/0.4 2.7 0.6 -0.39 0.86 -0.31
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(up to 19 in S. crassipes [4742]). Vessel walls (2–)4–6(–10) μm thick. Tyloses not
observed. Vessel element length (390–)740–1080(–1510) μm. Perforation plates sca-
lariform with few to numerous bars (up to 27 in S. elongata [4659]), reticulate and
simple (not observed in S. crassipes [4701, 4797]), in more or less oblique end walls.
Intervessel pits opposite and transitional to scalariform (in S. elongata [3353], S. emili-
ana, S. gordonii, S. pachyphylla, S. taomensis), and alternate; rather small (4–8 μm in
vertical diameter) in S. crassipes [4701], S. elongata and S. veillonorum [4774], and
larger (7–10 μm in vertical diameter) in other species, rounded and oval, with slit-like
apertures. Vessel-ray and vessel-axial parenchyma pits simple and half-bordered with
small borders, similar to intervessel pits in size and shape. Helical thickenings absent.
Vasicentric and vascular tracheids not observed.
Fibres libriform, mostly thick-walled ((2–)5–10(–14) μm), mostly non-septate (sep-
tate fibres rarely present in S. crassipes [4701], S. elongata, S. emiliana, S. gordonii,
S. taomensis [4742], and also in S. veillonorum [4784], where they are located mostly
in the immediate vicinity of rays), with few simple to minutely bordered pits with
slit-like apertures in radial walls.
Axial parenchyma scanty paratracheal in solitary strands near vessels, and also
diffuse in solitary strands (commonly containing crystal-bearing chambered cells)
located in immediate vicinity of rays in S. crassipes, S. elongata, S. emiliana, and
marginal in tangential interrupted lines in S. elongata [3353]. Strands composed of
(3–)4–7(–10) cells.
Rays 2–6 per mm, uni- and multiseriate of 2–5 cells in width (2–3 in S. crassipes,
S. gordonii, S. neocaledonica, S. taomensis [4742], and 2–5 in S. emiliana and S.
veillonorum [4784]). Ray height less than 0.7 mm (up to 0.9 mm in juvenile wood of
S. emiliana). Multiseriate rays composed of procumbent body cells (Kribsʼ type Ho-
mogeneous I predominant in S. crassipes [4701] and S. veillonorum) or also of square
and upright cells forming 1–2 marginal rows (up to 4 in S. elongata and S. taomen-
sis) (Kribsʼ type Heterogeneous IIb predominating in other species); solitary sheath
cells rarely present in S. elongata and S. pachyphylla, absent in other species. Multi-
seriate portions of rays usually distinctly wider than uniseriate portions. Uniseriate
rays composed of square and upright as well as procumbent cells. Radial canals not
observed. Crystals not found in ray cells.
Prismatic calcium oxalate crystals present in chambered (rarely non-chambered)
cells of diffuse parenchyma in S. crassipes, S. elongata and S. emiliana, and also in
septate fibres in S. elongata, not observed in ray cells.
→
Fig. 17–20. Species of the “Gabriellae” group. — 17 & 18: Scheffelra pancheri (Lowry 4661);
17: TS, growth ring boundary indistinctly marked by zone of relatively thin-walled fibres
mixed with solitary strands (arrows) of marginal axial parenchyma; 18: TLS, mainly homoge-
neous rays. – 19 & 20: S. gabriellae (Lowry 3297); 19: TS, growth rings absent; 20: TLS,
heterogeneous rays with 1 or 2 marginal rows of square and upright cells, radial secretory
canals (arrows). — Scale bar = 100 μm; magnification of Fig. 17, 18 & 20 as in Fig. 19.
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Legends on page 317.
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via free accessTable 5. Wood anatomical features of the “Gabriellae” species.
1: Annual rainfall (mm) — 2: Type of substrate (+ = ultrabasic; ± = intermediate; – = non-ultrabasic) — 3: Radius of wood sample (mm) — 4: Aver-
age length of vessel elements (μm) — 5: Tangential diameter of vessels (average / maximum, μm) — 6: Percentage of solitary vessels / the greatest
number of vessels in a vessel group — 7: Vessel frequency (per sq. mm) — 8: Usual / min.-max. number of bars per perforation plate — 9: Average
length of libriform fibres (μm) — 10: Width of multiseriate rays (average / maximum, cells) — 11: Height of multiseriate rays (average / maximum,
mm) — 12: Number of multiseriate rays per mm — 13: Number of uniseriate rays per mm — 14: Scores of Factor 1 — 15: Scores of Factor 2 —
16: Scores of Factor 3.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
S. gabriellae
(Lowry 3297) 1300 – 28 864 82/112 24/5 27 3/0-14 1025 3.8/6 0.3/0.5 3.6 0.5 -0.74 0.77 -0.61
S. gabriellae
(Lowry 4648) 1700 + >50 1129 87/116 33/4 20 5/0-30 1278 3.4/5 0.4/0.7 2.2 0.2 -2.20 1.28 -0.80
S. gabriellae
Oskolski & Lowry II — Wood anatomy of Schefflera
(Lowry 4681) 3000 + >30 1116 76/100 28/4 18 7/1-30 1344 2.8/4 0.4/0.6 2.8 0.3 -1.63 1.16 -0.31
S. gabriellae
(Lowry 4755) 2000 – 38 913 66/100 30/7 17 2/0-26 1179 3.5/5 0.3/0.4 3.2 0.3 -0.97 0.83 -0.80
S. pancheri
(Sarlin 302) >50 1235 96/149 22/5 18 4/1-33 1469 3.4/6 0.4/0.7 2.4 0.3
S. pancheri
(Lowry 4661) 1700 + >40 1272 80/100 7/16 40 3/0-16 1406 4.1/6 0.5/0.8 2.5 0.6 -1.61 1.29 2.02
S. pancheri
(Lowry 4721) 1700 – 45 1083 65 /84 21/6 26 2/0-24 1249 3.3 /5 0.3/0.4 2.6 0.4 -1.27 0.92 -0.39
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The “Gabriellae” group (Fig. 17–20, 24; Table 5)
Material studied: Schefflera gabriellae Baill.: Ile des Pins, Lowry 3297; Mt. Dzumac, Lowry
4648; Col de Yaté, Lowry 4681; Mandjélia, Lowry 4755. – S. pancheri Baill.: Mt. Dzumac,
Lowry 4661; Plateau de Dogny, Lowry 4721; sine loc., Sarlin 302; sine loc., Lw s.n. (ex CTFTw
6200, identified as S. andreana Baill.).
Diagnostic characters — Vessels wide (diameter often exceeding 90 μm), perforation
plates scalariform and simple, intervessel pitting mostly opposite to alternate, septate
fibres absent, multiseriate rays composed of procumbent body cells only, or with 1–2
marginal rows of upright and square cells, rays less than 4 per mm, less than 0.8 mm
high, crystals rarely present in non-chambered cells of marginal axial parenchyma.
Growth rings indistinctly marked by tangential zones of relatively thin-walled fibres
and interrupted marginal rows of axial parenchyma, and by somewhat smaller vessels
in S. pancheri [4661], absent in other samples.
Vessels rounded, rarely angular in outline, rather wide (average tangential diameter
> 65 μm, up to 116 μm in S. gabriellae [4648]), not numerous (vessel frequency from
17 per mm2 in S. gabriellae [4755] to 40 per mm2 in S. pancheri [4661]). Vessels
mostly in radial multiples of 2–3 (up to 16 in S. pancheri [4661]) mixed with soli-
tary ones. Vessel walls 2–6 μm (to 10 μm) thick. Tyloses noted in both S. gabriellae
[4648, 4755] and S. pancheri [4661]. Vessel element length (640–)860–1270(–1720)
μm. Perforation plates scalariform with few to numerous bars (up to 33 in S. pancheri
[Sarlin 302]) or simple (exclusively scalariform in S. pancheri [Sarlin 302] and S.
gabriellae [4681]), and reticulate, in more or less oblique end walls. Intervessel pits
mostly alternate, rarely transitional to scalariform and opposite, 5–8 μm in vertical
diameter, rounded and angular (mostly rounded in S. pancheri [Sarlin 302]), with slit-
like and lens-like apertures. Vessel-ray and vessel-axial parenchyma pits half-bordered
or with indistinct borders, scalariform to oval and rounded in outline, similar to in-
tervessel pits in size, with lens-like, oval, or slit-like apertures. Unilaterally-compound
pits not observed. Helical thickenings absent.
Vasicentric and vascular tracheids not observed.
Fibres libriform, thin- to thick-walled ((3–)5–7(–12) μm thick, up to 15 μm thick
in S. pancheri [4661]), all non-septate, with simple to minutely bordered pits with
slit-like apertures in radial walls.
Axial parenchyma scanty paratracheal or narrowly vasicentric in solitary strands
and incomplete sheaths. Uniseriate marginal rows of axial parenchyma also present in
S. pancheri [4661]. Strands composed of (3–)4–8(–10) cells. Non-chambered (rarely
Fig. 21–24. Calcium oxalate crystals in cells of axial and ray parenchyma. — 21: Schefflera
elongata (Lowry 4659). RLS, crystaliferous strands of diffuse axial parenchyma. – 22: S.
elegantissima (Lowry 3801). RLS, heterogeneous rays with prismatic crystals in upright and
square marginal cells. – 23: S. elongata (Lowry 4659). RLS, prismatic crystals in chambered
axial parenchyma cells. – 24: S. pancheri (Lowry 4661). RLS, prismatic crystals in chambered
cell of marginal axial parenchyma. — Scale bar = 100 μm; magnification of Fig. 21 as in
Fig. 22; that of Fig. 23 as in Fig. 24.
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chambered) cells containing prismatic crystals observed in strands of marginal axial
parenchyma in S. pancheri [4661].
Rays 2– 4 per mm, uni- and multiseriate of 2–6 cells in width. Ray height commonly
less than 0.6 mm, exceeding 0.8 mm in S. pancheri [4661] only. Multiseriate rays
composed of procumbent body cells; upright and square cells rarely present (Kribsʼ
type Homogeneous I) in S. pancheri; or forming 1–2 marginal rows and sometimes
incomplete sheaths (Kribsʼ type Heterogeneous IIb) in S. gabriellae. Uniseriate rays
Fig. 25–29. Perforation plates, SEM. — 25: Schefflera vieillardii (Lowry 4747). Scalariform
perforation plate with numerous bars. – 26–28. S. neocaledonica (Lowry 4656); 26: Reticulate
perforation plate; 27: Scalariform perforation plate with numerous bars; 28: Perforation plates
with few bars. – 29: S. vieillardii (Lowry 4747). Simple perforation plate. — Scale bars of
Fig. 25–27 = 10 μm; of Fig. 28 & 29 = 100 μm.
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composed of both upright and procumbent cells. Radial canals present in S. gabriellae
[3297] and S. pancheri [4721, Sarlin 302], bordered by numerous small, thin-walled
epithelial cells. Crystals not observed.
Fig. 30–32. Intervessel pitting, SEM. – 30: Schefflera vieillardii (Lowry 4747). Scalariform pit-
ting. – 31: S. elegantissima (Lowry 4715). Transitional pitting. – 32. S. neocaledonica (Lowry
4656). Alternate pitting. — Fig. 33 & 34: S. elongata (Lowry 4659). SEM, prismatic crystals
in chambered axial parenchyma cells. — Fig. 35 & 36: S. elegantissima (Lowry 4715). SEM,
prismatic crystals in ray cells. — Scale bars = 10 μm; magnification of Fig. 35 as in Fig. 36.
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NUMERICAL ANALYSIS
The loadings of the five factors with the greatest influence in the Principal Compo-
nents Analysis (PCA) are shown in Table 6. Together they explain 79.3% of the total
variation, with the first three alone accounting for more than 60% of the variation.
The scores of the three most important factors are given for each of the four groups of
New Caledonian Schefflera in Tables 2–5. The pattern of within-sample variation of
wood characters and of the environmental variables examined (summarized by the
distribution of the scores of Factors 1 and 2) is presented in Figure 37. Two well-
delimited clusters can clearly be seen. The samples from Schefflera sect. Schefflera
are completely separated from all others along the axis of Factor 2, with the remain-
ing samples forming a broad cluster stretching across the axis of Factor 1. Within this
second cluster, comprising the members of Dizygotheca and the “Canacoschefflera”
and “Gabriellae” groups, three non-overlapping but essentially contiguous sub-clus-
ters can be recognized, each corresponding to one of the species assemblages. In the
projection of sample variation against Factors 1 and 3, however, no clearly delimited
clusters can be seen, although the four taxonomic groups under study can be recog-
nized as sub-clusters with only limited overlap.
“Canacoschefflera”
“Gabriellae”
Dizygotheca
sect. Schefflera
Fig. 37. Pattern of within-sample variation of wood characters and of environmental variables
for New Caledonian Schefflera species (summarized by the distribution of the scores of Factors
1 and 2 from the Principal Components Analysis).
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Table 6. The loadings of the five factors with the greatest influence in the
Principal Components Analysis.
Factors Variance Variables Factor
% loadings
1. 27.4 average length of vessel elements -0.70
average length of fibres -0.77
average diameter of vessel lumina -0.87
average vessel frequency per mm2 0.78
average number of uniseriate rays per mm 0.74
2. 22.8 level of the intervessel pitting specialization 0.85
(sensu Bailey)
abundance of septate fibres -0.85
maximal width of rays -0.72
average height of rays -0.77
3. 12.7 percentage of solitary vessels -0.85
maximal number of vessels per group 0.71
4. 9.0 no significant correlations with any of the characters
examined
5. 7.4 annual rainfall 0.71
DISCUSSION
The New Caledonian species of Schefflera show a considerable range in diversity in
their wood structure: only two features, the presence of scalariform perforation plates
and of scanty paratracheal axial parenchyma, appear to be constant throughout the
taxa examined. These characters are also typical for a number of other Schefflera
species studied from various parts of the world, including South China, Indo-China,
Australia, New Zealand, Fiji, South America, and East Africa (Oskolski 1995).
The pattern of wood structure diversity within the taxa studied generally agrees
with the recognition of four species groups among New Caledonian Schefflera based
on macromorphology. Results of the Principal Component Analysis suggest that Di-
zygotheca, “Canacoschefflera” and “Gabriellae” represent natural assemblages, and
further indicate that they are closely related to one another. The PCA also suggests a
more isolated position for Schefflera sect. Schefflera, which likewise comprises a
natural group.
The members of “Canacoschefflera” are similar to those of “Gabriellae” in their
overall wood anatomy, suggesting a close relationship. “Canacoschefflera” can, how-
ever, be distinguished by having smaller vessels (less than 90 μm in tangential diam-
eter) that are more numerous (usually more than 30 per mm2), and also by more
numerous rays (up to 6 per mm) and the presence of solitary septate fibres.
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The occurrence of crystals in chambered cells of axial parenchyma, observed here
for the first time in Araliaceae in three species belonging to the “Canacoschefflera”
group (S. crassipes, S. elongata (Fig. 21 & 22) and S. emiliana), and also in one sam-
ple of S. pancheri [4661] in the “Gabriellae” group (Fig. 24), could be regarded as
additional evidence of a close relationship between these taxa. It should be noted that
diffuse axial parenchyma (Fig. 11) is a rather uncommon wood character for Araliaceae.
Besides its presence in Schefflera, this feature has also been recorded in the members
of two well defined groups centered in New Caledonia and Australasia, one compris-
ing Myodocarpus, Delarbrea, and Pseudosciadium (Oskolski et al. 1997), the other
with Apiopetalum and Mackinlaya (Oskolski & Lowry 2000), each of which appears
to represent a basally branching lineage within the order Apiales (= Araliaceae and
Apiaceae) (Plunkett & Lowry 2001).
The occurrence of crystalliferous chambered cells in the axial parenchyma of
Araliaceae could be of value for clarifying relationships between this family and its
apparent allies. Recent molecular evidence has clearly established a close relationship
between Apiales and Pittosporaceae (Chase et al. 1993; Plunkett 1994; Plunkett et al.
1996, 1997), as suggested earlier on the basis of vegetative anatomy (Van Tieghem
1884), floral morphology (Jurica 1922) and base chromosome number and chemo-
taxonomy (Jay 1969; Hegnauer 1971), and formalized in Dahlgrenʼs (1980) classifi-
cation system. However, on the basis of wood anatomy, Carlquist (1981) questioned
such a relationship, primarily because of the apparent absence of axial parenchyma
bearing crystals in chambered cells in both Araliaceae and Apiaceae. The occurrence
of this feature in several species of Schefflera appears, however, to refute Carlquistʼs
interpretation. While our data do not suggest a direct relationship between Schefflera
and Pittosporaceae, they do show that this feature occurs in Apiales and that it would
be worth examining other members of the order for its presence.
Based on wood anatomy, members of Dizygotheca appear to be rather close to
those of the “Canacoschefflera” group (Fig. 37). They can, however, be separated by
a number of features: the former have somewhat narrower and more numerous ves-
sels, almost exclusively scalariform perforation plates, a predominance of scalariform
intervessel pitting, more abundant septate fibres, more numerous rays (6–10 per mm
as compared with 3–6 per mm in “Canacoschefflera”) with 1– 4 (up to 10) rows of
upright and square marginal cells Kribsʼ type Heterogeneous I (vs. 1–2 (up to 4) mar-
ginal rows in “Canacoschefflera”), a peculiar shape of the multiseriate rays (with the
multiseriate portions of most rays as wide as the uniseriate ones), and also the distri-
bution of crystals (contained in ray cells and never in axial parenchyma). Most of
these distinctions are quantitative and vary more or less continuously; a sharp bound-
ary between the two assemblages can only be seen in two characters, i.e., the type and
morphology of rays. The wood structure of members of Dizygotheca appears to be
less advanced (sensu Bailey) than in species of “Canacoschefflera” and “Gabriellae”,
as indicated by their almost exclusively scalariform perforation plates and a predomi-
nance of scalariform intervessel pitting. Our data are consistent with Lowryʼs (1989)
suggestion that Dizygotheca is close to “Canacoschefflera”, and that the latter is in
turn related to “Gabriellae”.
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via free accessOskolski & Lowry II — Wood anatomy of Schefflera 327
The wood structure of Schefflera plerandroides, previously placed in the segregate
genus Octotheca (Viguier 1906; Hutchinson 1967), shows no essential differences
from that of other members of the Dizygotheca group examined. Wood anatomy thus
supports the hypothesis that polymerous flowers have evolved independently at least
twice within the Schefflera alliance, once in the Dizygotheca group (i.e., in S. pler-
androides) and a second time in the species traditionally referred to Tupidanthus and
Scheffleropsis (now included by most authors in Schefflera; cf. Frodin 1975; Lowry
et al. 1989), which appear on the basis of wood structure to be closely related to
Schefflera subsections Octophyllae and Heptapleurum (Oskolski 1994, 1995, 1996).
The interpretation of an independent origin of polymery is further supported by re-
cent molecular data (Wen et al. 2001), which suggest a close relationship between
Tupidanthus and several other Asian species assigned to Schefflera, but indicate the
placement of the Dizygotheca group in a separate clade comprising largely Pacific
taxa in several genera.
Comparing the results obtained here with the general classification scheme of
Schefflera based on wood anatomy proposed by Oskolski (1995), the members of
the “Canacoschefflera” and “Gabriellae” groups can clearly be referred to the previ-
ously recognized Group D, which also includes taxa from Africa and America. Two
subdivisions were initially proposed (D1 and D2) primarily on the basis of their ray
types (Kribsʼ type Homogeneous I and Heterogeneous IIb respectively), but their
validity now appears less reliable in the light of recent studies of a larger set of sam-
ples from Africa and South America (Oskolski & Lowry, in prep.). The position of
members of “Canacoschefflera” and “Gabriellae” within Group D is, however, some-
what isolated, as indicated by such rather primitive (sensu Bailey) wood features as
the presence of relatively long vessel elements and the occurrence of scalariform
perforation plates with numerous (more than 10) bars, and also by small vessels (tan-
gential diameter commonly less than 90 μm in “Canacoschefflera”), the scarcity or
complete absence of septate fibres, and the tendency to form prismatic calcium oxalate
crystals in the axial parenchyma cells. As for the members of Dizygotheca, they can-
not be ascribed to any of the subdivisions proposed in Oskolskiʼs (1995) classification
scheme, making it necessary to recognize a new Group E.
The three New Caledonian species of Schefflera sect. Schefflera differ very dis-
tinctly from other members of the genus by their very large rays and abundant septate
fibres, and are clearly referable to Group C2 of Oskolskiʼs (1995) classification scheme.
Wood anatomical data thus confirm Lowryʼs (1989) suggestion of a close relationship
between these species and the other members of the section studied to date. Specifically,
the wood of the species in New Caledonia is more similar to that of the Fijian endemics
S. vitiensis (A. Gray) Seem. and S. euthytricha A.C. Smith (which have a very primi-
tive wood structure) than it is to the more highly specialized wood of S. digitata from
New Zealand (Oskolski 1995). However, the New Caledonian species differ distinctly
from other members of this group by the co-occurrence of both simple and scalariform
perforation plates (the two Fijian species have almost exclusively scalariform perfo-
ration plates, whereas S. digitata is characterized by exclusively simple perforations),
which represents an intermediate level of specialization of their wood structure.
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