The Genus Iris, Apogon Section
THE APOGON SECTION
This section of the Iris genus has already been defined at p. 13 as containing all those species of rhizomatous Irises, in which the central line of the falls is either smooth or only covered with a pubescence of unicellular processes.
It seems, unfortunately, impossible to select any one character or set of characters to form a guide through the maze of species. The nearest approach to such a character is found in the seeds, but, besides the fact that these are often missing in herbarium specimens, those of a few species, such as Bungei and Rossii, are still undescribed. Moreover, the seeds of the species in each group are readily distinguishable and have only a certain family likeness, which indeed in some cases is only apparent to the practised eye.
The classification of the Apogon species given below is therefore admittedly unsatisfactory, partly for the reasons already given, and partly also because some of the species seem to stand by themselves and to have little affinity to any others. Under each heding in the following list an attempt is made to give the chief characteristics of the species inch1ded.
I. The sibirica group
has seven representatives in Eastern Asia, one in Europe and one in America. Stems hollow (except in I. Clarkei and I. prismatica ) ; capsule trigonal ; seeds disc-shaped, D-shaped, or cubical ; leaves thin and grassy ; perianth tube ·short, not smooth but obviously formed of the con cretion of the bases of the segments. Stigma a projecting triangular tongue. See p. 19.
I I. The tenuijolia group. This group of Central Asiatic I rises consists of plants with short un branched stems, and rigid, linear leaves. The growths are very crowded and the bases of the leaves seem to persist for several years, and form dense bundles which in the wild state have the appearance of being either burnt or browsed off. The root fibres are very wiry. [N.B. I. songarica seems to be a connecting link between this group and the spuria group.] See p. 32.
I I I. The Californian group. Rhizomes slender, root-fibres few in number. Leaves tough and leathery, scanty, pink at the base. Seeds light brown or buff, spherical, thick D-shaped or even almost cubical. The dying leaves turn a dull red, quite distinct from the usual brown colour of withering Iris foliage. See p. 35.
IV. The Syrian group. Rhizome annulate and surrounded with stiff bristles. Spathes very long and narrow, one flowered with the pedicel equal m length to the spathe. See p. 45.
V. The Chinese group consists of four species of slender growth, of which apparently only one is in cultivation. I. minuta and I. Henryi are probably allied to one another. The other two are grouped with them by reason of their geographical proximity and not of any known structural affinity. See p. 46.
VI. The scarlet-seeded Iris. The single character of the scarlet seeds, that remain attached to the open capsule, seems sufficient to separate I. foetidissima from all other species. Confined to Europe and North Africa. See p. 50.
VI I. I. ruthenica with its dwarf grassy growth and prominent white excrescence on the fresh seeds seems also to stand entirely alone. This species is found in Hungary, m the Altai region, and thence eastwards as far as Pekin. See p. 52.
VII I. I. unguicularis is distinguished by its tough foliage, close-matted growth, long perianth tube and undeveloped stem, and also'y the curious and characteristic processes that cover the upper surface of the style branches. See p. 54.
The type is found in Algeria but subspecies also occur in Greece, Crete and Asia Minor, as far east as Alexandretta and Lazistan. See p. 56.
I X. The spuria group. The chief characteristics of this group are the double ribs at the angles of the capsules, the loose parchment-like skins of the seeds, the two-toothed stigma, and the panduriform outer segments. Leaves ensiform, tough, emitting a slightly fetid odour when bruised. I ts representatives are widely distributed through Europe and Asia as far east as Kashmir. See p. 57.
X. The laevegata group. Seeds more or less D-shaped, with smooth polished skins. This group is represented in Eastern America. Europe and Eastern Asia. See p. 7 2.