Special ML orphology and Classification. 351 
‘Cohort V. DioscoraLEs. Flowers dicecious, reguiar; perianth herba- 
ceous ; stamens six, inserted at the base of the perianth-segments ; 
ovary trilocular ; fruit a berry or capsule ; seeds with copious fleshy 
endosperm, and a distinct included embryo. Climbing herbs or smal] 
shrubs, with netted-veined leaves. Order Dioscoreacee (Dioscorea, Tamus, 
Testudinaria). 
Division III. Flowers petaloid. Ovary superior. 
Cohort VI. POTAMALES. Ovary apocarpous (rarely reduced to one 
carpel); flowers hermaphrodite or unisexual ; perianth of three, four, 
or six segments, or absent ; stamens one to six ; seeds exalbuminous ; 
embryo conspicuous. Usually water-plants. Principal orders :— 
Butomacee (Butomus); Alismacee (Alisma, Sagittaria) ; LPotamee 
(Potamogeton); Natadee (Zostera, Natas). 
Cohort VII. PALMALES. Ovary syncarpous (rarely apocarpous); 
flowers unisexual, arranged ona simple or branched spadix, enclosed 
in a spathe or not ; perianth of distinct bi-seriate coriaceous segments, 
green, rarely coloured or absent; fruit a one- rarely two-seeded drupe 
or berry; seed albuminous. Shrubs or trees with flabellate or pinnately 
divided, rarely simple leaves. 3 
Order 1. PALM. Flowers usually diclinous ona branched spadix; 
perianth green ; stamens usually six, hypogynous or perigynous ; ovary 
tri- rarely uni-locular, or of three separate carpels ; styles short, free or 
connate; loculi with one, rarely two, ovules; seed large ; embryo 
minute, sunk in a pit of the fleshy or horny endosperm. ‘Trees or 
shrubs.] Although the Palms appear to belong to the more highly 
developed Monocotyledons from their stately arborescent stems and their 
large leaves, the insignificance of their flowers reminds 
one of the lower families, and the habit of many 
species even of the Grasses; while the structure of the 
flower and inflorescence allies them to the Arales 
(Figs. 469, 470, 471). The stem is usually simple, 
rarely dichotomously branched, as in the doom-palm, 
generally erect, sometimes climbing, as in the rattan, 
and commonly bears a crown of leaves only at its 
summit. The leaves, often called fronds,, are Fic. 469. — Flower 
fan-shaped in the fan-palms, pinnate in the feather- ee Pre 
palms, rarely undivided. The flowers are placed on Chamerops hi. 
a simple or branched rachis, which is surrounded in 7 
vernation by a common envelope or sfathe ; they are originally perfect, 
but almost always become, in the course of development, diclinous or 
polygamous from the abortion of stamens or pistils, The six perianth- 
