This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
A familiar genus very numerous in species, and among the most ornamental of hardy monocotyledonous plants. Herbs with fleshy rhizomes, or in a few species bulbous or with fibrous roots. Leaves sword-shaped or linear, often equitant. Perianth-tube short, with the three outer segments reflexed, often bearded at the base, and the three inner erect, generally smaller than the outer. Stamens 3, inserted at the base of the outer segments; anthers turned outwards. Style triquetrous, with 3 petaloid stigmas opposite the stamens. Capsule 3-celled, many-seeded. Natives of the northern hemisphere, chiefly in temperate Europe and Asia. Name from the Latin iris, the eye. The species are naturally divided into two distinct sections: - the one with ensiform leaves and creeping rhizomes or fleshy fibrous roots; and the other with bulbous roots and usually flat or incurved leaves. Amongst the ensi-form group we may mention : 1. I. Susiana. - A Persian species introduced into. Europe towards the end of the sixteenth century. It is a gorgeous plant, possessing the largest flowers in the genus, and growing about 2 feet high. In this species the inner segments of the perianth are the largest; all are of a lurid grey or brown, reticulated with dark purple, and the outer ones strongly bearded. Flowering in April and May.
2. I. Germanica (fig. 229). - This is the commonest of this section in cultivation. It is a native of Central Europe, and extremely hardy. There are numerous varieties, and many of them are strikingly handsome. The prevailing colour is some shade of blue or violet, occasionally yellowish or white, and prettily reticulated. The segments of the perianth are nearly equal. Leaves large and fleshy; stems several-flowered; flowers stalked. The flowers appear from May to July.
3. I. Florentina. - Scarcely differing from the last, but distinguished from it by its quite white flowers rayed with pale yellow on the outer divisions. The rhizome is odoriferous and officinal, under the name of Orris-root.
4. I. variegata. - From Austria and Hungary, with linear channelled leaves and large yellow flowers, whose exterior segments are bearded and marked with brown, and bordered with pale rose.
5. I. lurida. - A South European species with robust broad leaves and medium flowers, brownish violet tinged with yellow.
6. I. spuria. - Native of Spain and Barbary, having long acute leaves and bright blue medium flowers with a large bright yellow spot on the three outer segments. Not so hardy as some.
I. ochroleuca is similar to the foregoing, from the same countries, and probably only a variety of it. Flowers of a yellowish white with a blotch of bright yellow on each of the outer perianth-segments. I. versicolor is a dwarf North American species with short leaves and much smaller flowers than in any of the preceding, of a violet brown with a bright yellow spot on the very broad limb of the three outer segments. I. cristata also a North American species, of very diminutive stature, about 6 inches high, and very short leaves. Flowers below the middle size, geminate, of a bright blue, with a yellow spot on the outer segments. May or June. I. pratensis, syn. I. Sibirica, is a native of Central Europe and Russia. A pretty plant with grass-like leaves and blue flowers.
Fig. 229. Iris Germanica. (1/4 nat. size.)
7. I. Pseud-dcorus. Yellow Flag. - This is the common indigenous species, growing about a yard high, with long acute bright green leaves and large clear yellow flowers. Suitable for lakes and swampy places.
I. Monnieri, from S. Europe, is a similar plant, with larger and brighter yellow flowers.
8. I. fimbriata. - Of Chinese origin, and one of the handsomest of the genus. Flowers large, of a bright blue variegated with dark brown on the outer segments, which are undulated. Stigmas erect, petaloid and fringed. A tender species.
9. I. arendria. - The dwarfest of the genus, from 2 to 4 inches high. Flowers scarcely exceeding the leaves, of a uniform yellow. A native of the sandy plains of Hungary.
We now come to the bulbous section, which is by no means so numerous in species as the foregoing.
10. I. Xiphium (fig. 230). - Commonly known in English gardens as the Spanish Iris. Stems from 9 inches to a foot high, and furnished with narrow acute leaves. Flowers of medium size, two or three together, with narrow nearly equal segments. The natural colour is an azure blue, but there are many varieties in cultivation ranging through all shades of blue, associated with yellow and chestnut.
11. I. xiphioides. English Bulbous Iris of florists. - Slightly different from the last, but usually 1-flowered, and the flower larger. The three exterior segments are of a bright yellow, with an orange spot in the centre of the limb, the three interior blue or violet. There are also many beautiful garden varieties of this species. This and the last are both natives of South-western Europe.
12. I. spectabilis. - Similar in habit, but taller than the two last. The outer perianth-segments brownish, with a large orange blotch in the middle of the limb; the three interior of a deep violet.
13. I. Persica. - A charming plant from Western Asia, formerly widely spread in gardens, but now become rather rare.
Fig. 230. Iris Xiphium. (1/4 nat. size.)
It is distinguished from the preceding by its dwarf stem and early flowers, which appear towards the end of Winter, before the leaves are fully developed. It is very hardy and admirably adapted for edging beds or borders.
14. I. tuberosa. - From Greece and Western Asia. Like the last, it was formerly in great request in our gardens, but has now also fallen into oblivion. The flowers are rather above the medium size, with the three outer segments of a dark purple, slightly reflexed and arched; the three interior are erect and greenish. This is a very hardy species, flowering a little later than the Persian.
15. I. reticulata. - From the Crimea, differing in more than one respect from all the other species here enumerated. Each flowering stem bears only two leaves, which are quadrangular and longer than the stems. The flowers are solitary, with a long tube, giving them the appearance of being pedunculate. Their colour is of the brightest purple variegated with mar-blings of a darker tint and a large spot of yellow on the outer segments, with a delicious odour of violets. This is a very hardy and extremely handsome species.
16. I. scorpioldes. - An Algerian species, differing from all the foregoing in its leaves, which are almost flat.and very like those of the common Leek. The flower is solitary, of a very bright blue, with a yellow spot on each of the outer segments. The three interior perianth-segments are small and inconspicuous. It requires slight protection.