FAMILY ОЕ FLOWERING PLANTS. 51 
The characters of the two families may then be given briefly as follows :— 
TRISTICHACE. Perianth 3—5-merous, regular, free or united, sepaloid, 
marcescent. Stamens 3, 5, 20-25, ог 7, or 1, usually alternate with perianth. 
Ovary 2-3-locular with o anatropous ovules. Capsule stalked, septifragal, 
ribbed, with equal lobes and © seeds. Herbs with numerous large secondary 
shoots from the creeping roots (except Lawia, which has the primary shoot 
flattened into a creeping thallus), bearing delicate, minute, simple exstipulate 
leaves. 
PoposrEMACEA. Flower achlamydeous, enclosed before opening in a 
spathe springing from the base of the stalk, regular or irregular. 
Stamens co or few ог 1, ina whorl, or on lower side of flower only, free or 
united, with usually as many staminodes. Ovary 2-1-locular, with oo or few 
anatropous ovules. Capsule stalked or sessile, ribbed or smooth, septifragal 
or indehiscent, with œ or few seeds. Herbs with creeping roots of great 
variety of form, bearing secondary shoots also of great diversity of form. 
Leaves usually large, much branched and complicated, stipulate, the branches 
arising under special lower stipules. 
To consider in greater detail some of the points of difference :— 
(1) Perianth.—Spathe and staminodes. In the first place, are these 
staminodes? It would seem that they are, for this reason, When a flower 
becomes zysomorphic, there seems no tendency for the upper part of the 
perianth to disappear, with rare exceptions, while the upper stamens often 
do so, and most often, perhaps, leave no staminodes as traces. Now here, 
the upper stamens disappear, and with them the upper organs of which we 
are speaking. Hence it would at any rate appear probable that these are 
really staminodes. And staminodes do not appear in the other family, nor, 
except to some extent in Weddellina, do numerous stamens, which are so 
often found in the Podostemaceæ proper. 
The perianth then disappears, and is replaced by the spathe, but it is very 
difficult to regard this as homologous with it, for it shows no sign of being 
composed of any definite leaves, and it arises at the base and not the apex 
of the stalk, except in one African species *. In any case, the transition from 
one to the other state is very great. 
(2) Few stamens (exeept sometimes Weddellina).—Many stamens and 
staminodes. This transition would be easy, were the many stamens in the 
Tristichaceæ, which are on the whole the more primitive, but it is more 
difficult to go the other way, for the flower tends on the whole to become 
simpler with greater complexity and adaptation of the vegetative organs. 
* A new species of Tristicha which I have just discovered has two leaves at the base of 
the flower-stalk which may well represent the origin of the spathe, but otherwise it is 
tristichous, whereas the Podostemace proper are distichous. Ido not think that this 
discovery affects the real separation of these families, 
