BOTANY. 3 
species. Ex. Naias, Zannichellia, Potamogeton, Ruppia, Zostera, all of which 
have North American representatives. 
Potamogeton natans, or common pondweed, is abundant along the shores 
of still waters (pl. 55, fig. 1), a, the plant; b, a flower ; ¢, a sepal seen from 
behind; d, the same with the stamen from the inside; e, the four pistils ; 
f, a fruit; g, longitudinal section of the same. Zostera marina (fig.3), a, 
a plant reduced; 6, the upper part of a fertile branch; c, an opened spatha 
with the inclosed spadix; d, the lower part of a fruit-bearing spadix in the 
spatha; e, ananther from behind ; f, ovary ; @, ovary opened, showing the seed ; 
h, the seed; i, section of the seed showing the embryo. 
OrperR 14. AromE#, the Arum Family. Flowers generally unisexual, 
rarely bisexual, inclosed within a spatha, and usually on a spadix, having 
male flowers at its upper part, female below, and abortive flowers between 
them. Perianth either 0, or in the ¥ flowers rudimentary and scaly. 
Stamens definite or 00, hypogynous; anthers extrorse. Ovary free, one- to 
three- or more-celled; ovules solitary or numerous ; style short or 0; stigma 
simple. Fruit succulent or dry, indehiscent, uni- or pluri-locular: seeds one 
or several; embryo in the axis of fleshy or mealy albumen, sometimes with 
a lateral cleft for the plumule ; radicle usually next the hilum. Herbaceous 
or shrubby plants, often with. tubes or creeping rhizomes, leaves sheathing 
at the base, and having parallel or branching veins. They occur in dry and 
marshy places, and in lakes in various parts of the world, abounding in the 
tropics. 
This order has been variously subdivided; the most convenient division for 
our purpose, however, is into four sub-orders. 
Sub-order 1. Pistiee (Lemnacee) or Duckweeds. Flowers 4 ¢ naked, 
inclosed in a spatha without a spadix, ovary one-celled, ovules two or more, 
fruit membranous or capsular. Examples: Pistia, and Lemna or duck- 
weed. 
Sub-order 2. Acoree. Flowers ¥ having usually a scaly perianth, ar- 
ranged on a spathaceous spadix, ovules one or more, fruit a berry. Examples: 
Symplocarpus (S. foetidus or skunk cabbage); Orontium (O. aquaticum, never 
wet, or Golden club); and Acorus. <A species of this latter genus, Acorus 
calamus, found both in Europe and America, furnishes the calamus or swect 
flag, so much sought after by boys, and a favorite food of the muskrat (Fiber 
zibethicus). ‘This specious of Acorus is shown in pl. 55, fig. 4; a, an entire 
plant ; b, a spadix; c,a flower from above; d, the same from below; e, an 
unripe fruit; f, the same in vertical and g@ in transverse section; h, a leaf 
cut across (right hand of the plate). 
Sub-order 3. Typhineae. (Typhaceae). Bulrushes or Cat-tails. Marsh 
herbs, with nerved and linear sessile leaves, and monececious flowers on a 
spadix or in heads, destitute of proper floral envelopes. Fruit nut-like when 
ripe, one-seeded. Seed suspended, anatropous; the embryo straight in 
copious albumen. There are but two genera, Sparganium and ‘Typha. 
Typha latifolia is the common cat-tail of the swamps ( pl. 55, fig 5); 4a, 
the spadix with its spatha; 6, a cross-section of the male spadix; ¢, a male 
flower. 
73 
