The Apogon Section 
19 
XI. The hexagona group. Capsules with six ribs, more evenly distributed on the circumference 
than in the spuria group; flowers set in the axils of the leaves. Confined to the Eastern United 
States. See p. 81. 
XII. Iris etisala. Ovary six-grooved, passing almost imperceptibly into the pedicel, tube very 
short. Capsule long, narrow, almost spherical in section, with six ribs at equal intervals. Seeds smooth, 
pyriform, or slightly compressed. Leaves narrow, linear-ensiform. An Asiatic species. See p. 85. 
XIII. The longipetala group. The plants resemble I. eusata in the characters of the rootstock 
and foliage. The seeds are somewhat similar, but distinctly larger and not compressed. The capsules 
are broad at the centre and taper at either end. The group is confined to the Rocky Mountains and 
to the region lying between that range and the Pacific. See p. 89. 
XIV. The tripetalous group. The inner perianth segments or standards are reduced to little more 
than bristles. The members of the group are found in Eastern Asia, Alaska and along the east coast 
of North America. See p. 92. 
XV. Iris verna an anomalous species, with the habit of a Pogoniris but beardless. See p. 95. 
I. The Sibirica Group. 
This group of ornamental Irises consists of about nine species, all of which with the single 
exception of I. prismatica are natives of Europe or Asia. It is only within comparatively recent 
years that the group has been more than doubled in size by the addition of five new species 
from Western China, namely I. Delavayi , /. Wilsoni, I. Forrestii, /. Bui ley ana s and /. chrysographes. 
Of the older species, I. Clarkei was discovered near Darjeeling by Sir Joseph Hooker rather more 
than sixty years ago, I. orienlalis was described by Thunberg at the end of the eighteenth century, 
and /. sibirica was known to Clusius. The one American representative, /. prismatica , was first 
described by Pursh early in the nineteenth century. 
All the species agree in the possession of grassy leaves, produced in close tufts from the 
slender, much branched rhizomes. In all cases the root system is composed of masses of close- 
growing fibres, which are indicative of moisture loving Irises. Moreover, a hollow stem is found 
in seven of the nine species but nowhere else in the genus. Herbarium specimens are seldom a 
safe guide on this point, for the pith in the centre of a stem often shrivels and this leaves 
a hollow, although the living stem is solid. 
All the members of the group do best in soil that is rich in humus, for this tends to maintain 
a certain degree of moisture in the soil. For some reason, I. Delavayi seems to be perhaps the 
most exacting in this respect, for it obstinately refuses to flower unless abundantly supplied with 
moisture during the growing season. I. Clarkei , too, is scarcely easy to maintain in health. It 
grows in wet ground in the Himalayas in the neighbourhood of Darjeeling and seems to resent 
any attempt to cultivate it in too dry and hot a soil. In dry sandy soil, seedlings do well for a 
year or two and then usually succumb. 
I. sibirica and its allies all agree in the possession of a tongue-like stigma, which enables them 
to be independent of insects for fertilisation. In some cases the anthers actually reach the reflexed 
tongue of the stigma, while in others this tongue is able to gather the pollen that has fallen from 
the anthers on to the haft of the falls. In all cases the pollen is extremely easily shaken from the 
anthers, and it is indeed often difficult to extract an anther without losing most of the pollen. 
Seeds are accordingly easily obtained and, except perhaps in the case of I. Clarkei , germinate 
readily in spring, if sown in September or October and left in the open during the winter. When 
the young seedlings have produced four or five leaves, they should be planted out in their 
permanent quarters, where a fair proportion of them may be expected to flower in the following 
season. 
When transplantation of mature plants is necessary, it should be carried out in late summer or 
early autumn, before the young roots, which push out freely after the flowering season, have grown 
to any length. Unless it is desired to perpetuate any particular form, it is hardly worth while to 
divide clumps of these Irises since seedlings are so easily raised and usually produce a much better 
effect if allowed to grow undisturbed where they were originally planted out. It is not uncommon 
for plants to produce as many as ten or twelve flower stems, when they flower for the first time. 
The species that form the group may be differentiated as follows: — 
{Stem hollow. 
Stem solid. 
Inner segments (standards) erect. 
Inner segments (standards) extended obliquely. 
Leaves glaucous on both surfaces. 
Leaves glossy on the upper surface and glaucous beneath. 
1. 
7 - 
2. 
4 - 
3 - 
I. Forrestii (p. 27). 
3—2 
