Wednesday 29 June 2011

An under-rated Iris

Iris latifolia - the English Iris.
It is a mystery to me that Iris latifolia, one of the most striking irises, and an exceptionally good plant for naturalizing in grass, is so poorly known and seldom seen. Its common name is even English Iris, derived from a misunderstanding from 400 years ago, when Matthias de l'Obel saw it growing near Bristol and named it Iris bulbosa Anglica, a name that rapidly established itself in botanical literature and has stuck to the present day in the bulb catalogues, at least. It is in fact native to north-west Spain and both sides of the Pyrenees, growing in meadows, so must have been brought to England by traders at quite an early date. The species was known for a long time as Iris xiphioides, but Philip Miller's name I. latifolia has priority and is now in general use.

Iris latifolia in John Sales's garden.
 The bulb is quite large, with a shaggy dark tunic and strong roots: I don't think it likes to be dried out for long, which may partly explain its scarcity in gardens. The shoot emerges in early spring and the long narrow leaves expand until about early June, when they begin to die off as the flowering stem emerges. They're only broad-leaved (latifolia) in comparison with other bulbous irises in the Section Xiphium, such as I. xiphium itself and the prolific hybrid group of Dutch Irises. The inflorescence is about 40-45 cm tall, with a series of broad bracts towards the top, the uppermost two protecting the two flower buds. They sometimes open more or less simultaneously, giving the impression of being one very large flower with double the complement of floral parts (as seen below). The normal flower colour is deep purple blue with white and yellow on the falls, but many selections have been made for different colours, including white, pale blue and variously mottled (though I suspect this a viral effect). A reddish-purple form appears among seedlings in John Sales's garden, Covertside, just down the valley from here, and is rather striking.

A reddish-purple form that appears among seedlings at Covertside.
John Sales, former Gardens Adviser to the National Trust, has the finest display of English Irises I know, in the meadow garden he has created adjacent to his home. He and his wife Lyn have a coffee morning and plant sale each year for charity, timing it to coincide with the flowering of the irises, which were duly admired last Sunday. His are a few days ahead of mine, being a couple of hundred feet lower, but the more modest numbers in my 'long meadow' here are now at their peak and look lovely amongst Oxeye Daisies (Leucanthemum vulgare), Aconitum ferox and Astrantia major. I think it's helpful to grow them in grass, as it conceals the dying foliage somewhat; this year the earlier dry weather seems to have encouraged the leaves to die back earlier than usual, so they're showing yellower than they usually are at flowering time. Most flowers set seed, so although seedlings take several years to reach flowering size it is easy to raise a batch of seedlings. It ripens in August, so this is usually the signal to mow the grass before the autumn bulbs emerge, though of course mowing can occur at any time from now as the leaves have finished their work.

Iris latifolia in the meadow here. The dying leaves need to be concealed by tall vegetation.

1 comment:

  1. I am also surprised that these plants are not better known, they grow very well in heavy slightly acidic soil (Perthshire) where winters can be severe. They naturalise and increase easily in the right soil, I think they like a lot of rain.


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