February 2021 - Hardy Plant Society

February 2021

Welcome to the February 2021 edition of Shade Monthly.

We hope you enjoy the two articles included in this month’s edition of Shade Monthly.
Many thanks to Keith Ferguson for this article and wonderful photos of Californian Irises –
perfect to brighten up what can be a gloomy time of year. Many thanks also to Tricia
Howard of Hidden Valley Garden in Cornwall, for an exploration of Polypody ferns and their
variations. Both have given me a lot of inspiration for new things to try in the garden this
year.

As ever, please send any contributions to shademonthly@gmail.com. All articles of any
length and images are very welcome.

I hope you are all able to get out and enjoy your gardens as the seasons slowly change. As
the days begin to draw out, the first hardy snowdrops and green buds remind us that the
spring will surely arrive.

               The emerging flower buds of Helleborus x ericsmithii

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Californian Irises
Text and photos by Keith Ferguson

I was delighted to read Sue Lander’s article on Iris ‘Pinewood Amethyst’ and Californian
Irises, still called Pacific Coast Irises by many. I read with interest her advice on growing
these lovely plants and the brief history of the origin of some of the hybrids. I agree with her
advice about dividing clumps that as with I. unguicularis one needs to take a large piece with
plenty of rhizome and this is best done in the autumn when they are coming back into
growth after a summer rest.

I thought I could add more pictures and some information about them in the wild as they
are some of my favourite Irises.

Figure 1 Iris douglasiana in wild S.Oregon

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I have been interested in Californian Irises for some years due to regular visits to the west
coast of USA. I never really thought much about their cultivation, as we grew a few on
Bagshot Sand (the same soil as RHS Wisley I add) in partial shade in Surrey. I never regarded
the hybrid we had there as in any way difficult. On moving to heavy, neutral clay in west
Gloucestershire the plants we brought with us flourished in a sunny position near the house.
However, our interest was stimulated by seeing some amazing hybrids in the gardens of
members of the Hardy Plant Society of Oregon and then finding a number of the species in
the wild. Our first find was Iris douglasiana and I. innominata growing on the margins of a
coniferous forest clearing and where they met there was clearly a hybrid population with
the blue of I. douglasiana and the yellow of I. innominata. We went on to find at least 5 of
the 10 species recognised in Flora North America. Four of those 10 grow in the region south
of or around San Francisco and we have not visited that area in Iris season. Apart from the 2
mentioned we have found I.bracteata, I. tenax, I. purdyi and I. chrysophylla. They generally
grow in partial shade in clearings and on the margins of the coniferous forest of the west
coast of the USA mainly in northern California and southern Oregon and the soil is usually
acid. However. I. douglasiana grows frequently on cliff tops in open ground and is said to be
more lime tolerant. We certainly recall seeing many and very variable clumps on the cliffs
around the light house on Cape Blanco in southern Oregon. We managed to find some full
seed capsules from previous season in this locality and have raised a very variable selection
of plants in leaf width and flower colour.

Figure 2 Iris douglasiana in wild on sloping cliff top near Cape Blanco S.Oregon

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Figure 3 Iris innominata in wild S.Oregon in shade of coniferous forest

Figure 4 Iris bracteata in wild S.Oregon dappled shade in coniferous forest

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Figure 5 Iris tenax in wild in shaded hedgerow central Oregon

All if the species in the Group hybridise with one another and some with Iris siberica.
We decided to try some of the hybrids available in a small number of nurseries in the UK.
Here we found that in general the Broadleigh strain have done well as have those we have
raised from seed. Why they are not more popular or better known is a mystery as the
hybrids are not difficult and do not need acid soil and they flower in and about May and
they don’t need much attention. Easily raised from seed and one usually gets quite a range
of flower colour. One can only suppose that they fall in the domain of the specialist
nurserymen as they require time to bulk up. As regards cultivation it is quite clear that they
have not read some of the books on Iris!
A quick check in the current Plant Finder found there were some 3 Banbury named varieties:
6 Broadleigh, 2 Pinewood and 3 others. While of the species, some 5 are listed: I.bracteata,
I .tenax, I. tenuissima each with one entry and the big surprise that to me the easiest of the
species I. douglasiana is offered by only one nursery while to my surprise I. innominata is
offered by 11 nurseries and there are 2 variants offered by one of those nurseries.

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Figure 6 I.hybrid ‘Broadleigh Lavinia’ Glencoe Farm Garden

Figure 7 I.hybrid ‘Broadleigh Mitre’ Glencoe Farm Garden

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Figure 8 I.hybrid ‘Broadleigh Chelsea Yellow’ Glencoe Farm Garden

Figure 9 I.hybrid unnamed seedling from Broadleigh Glencoe Farm Garden very vigorous and floriferous in
both shade and open locations.

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Figure 10 I. hybrid seedling from Surrey garden and now in Glencoe Farm Garden

          Figure 11 I.hybrid unnamed seedling in an Oregon garden near Portland

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Polypodium ferns in Cornwall
Text and photos by Tricia Howard (Hidden Valley Gardens, Cornwall)
During lockdown I have been exploring our local area, and admiring our lovely ferns at the
same time. I have just got a new field guide ‘Britain’s Ferns’ by James Merryweather, which
contains lots of helpful photographs to aid identification.

One of my favourite ferns is the Polypodium, they like good drainage and semi shade and are
often found growing on top of roadside walls. There are three main types in Cornwall.
P.interjectum is the most common - see photo of the large clump on a bank at the charmingly
placed name of “Puddle” near Lanlivery. This patch must have taken many years to reach this
size.

      Fig 1 - Polypodium interjectum in Puddle

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Polypodium vulgare is widely spread throughout Cornwall often on granite moorlands and
oaks. See photo of a cultivar with forked and crested pinnae (fig 2). Polypodium cambricum
(syn P.australe) however is rarer in Cornwall and is mainly found in South East Cornwall. It
likes old, mortared walls with
lime and appears on Trematon
Castle, and in the St. Germans
area. Otherwise, it is found in
some parts of the South West,
Wales and Ireland. Polypodium
cambricum has evolved over
many      years,    from       the
Mediterranean regions where
the summers are hot and dry.
They are therefore dormant in
the summer, start to grow again
in the autumn, and are at their
best in the winter, when the
snowdrops are flowering.             Fig 2 - Polypodium vulgare ‘Bifido multifidum’

There are many really attractive varieties of P.cambricum, the best know is P.cambricum
‘Richard Kayse’, found by him on a sheer limestone cliff, in South Wales in 1668. Another
special one is P.cambricum ‘Prestonii’, which was found in Lancashire in 1871 by Mr Preston,
growing in a limestone pavement. It is an elegantly lacerated form, so he really wanted it. As
he was unable to extricate it, Mr Preston cut out the whole limestone block to take home and
grew it on from there, things were different in those days! Many P.cambricum varieties are
sterile and must be reproduced by division.

Fig 3 - Polypodium cambricum
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Fig 4 - P.cambricum (Pulcherrimum group)

Polypodium cambricum varieties
can be seen at the Garden House
and there is a national collection in
Kent. It is fun looking for variants,
and recently I came across a wild
crested form in SE Cornwall, which
is very unusual. Also, I have raised a
linear (narrow) form from spores.
British collectors have selected and
named many other cultivars over
the years. See photo (fig 4) of
P.cambricum           (Pulcherrimum
group), which means beautiful.
These Polypodiums look good in the
winter garden and in hanging
baskets which can be moved and
replaced by flowers in the summer
when they are dormant.

    Fig 5 - Polypodium cambricum
    ‘Cambricum’

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Fern and Arum Arrangement Jan. 2021

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