PODOSTEMACE^. ("RIVEB-WEED FAMILY.) 399 



cells confluent. Styles 2, slender: stigmas acute. Capsule 4-angled, 4- 

 celled, with a single suspended anatropous seed in each cell, indehiscent. 

 Embryo straight, in copious fleshy albumen. Radicle long, superior. — 

 Consisting of the single genus 



1. CALLITRICHB, L. Watbe-Staswobt. 



1- C. verna, L. Floating leaves spatulate or obovate, crowded, the lower 

 ones distant, linear; fruit nearly sessile, 2-bractcdv keeled on the back. (C. 

 heterophylla, £//.) — Var. terrestris. Smaller (2' -3' long); stems much 

 branched, creeping on damp earth ; leaves (l"-2"long) all linear. — Ditches 

 and shallow water, Florida, and northward. March and April. — Stems several, 

 6'- 12' long. Leaves J' long. 



Order 118. PODOSTEMACEiE. (Eiver-weed Family.) 



Moss-like aquatic plants, with minute flowers, from a spathe-like in- 

 volucre, and destitute of floral envelopes. — Stamens 5-12: anthers 

 2-celled. Capsule 2 - 3-celled, and pointed by as many persistent styles. 

 Seeds numerous, on a thick central placenta, destitute of albumen. 



1. PODOSTEMON, Michx. River-weed. 



Spathe 2-leaved. Flowers pedicelled. Filaments elongated, borne on one 

 side of the stalk of the ovary, united below, and bearing only a single anther. 

 Styles 2, simple. Capsule ribbed, 2-celled, 2-valved. Seeds imbricated. — 

 Submerged aquatic plants, attached to rocks and pebbles by disk-like expan- 

 sions of the stem. Leaves 2-ranked, divided into filiform segments. 



1 . P. ceratopliyllum, Michx. Leaves rigid, sparingly divided, sheath!- 

 ing at the base ; flowers solitary, on slender pedicels ; capsule oval, 8-ribbed. — 

 Rocky places in rivers, Georgia, and' northward. July. — Plant olive-green, 

 t'- 4' long. 



2. P. abrotanoides, Nutt. Leaves much divided, with hair-Uke seg- 

 ments ; flowers 2-3 together, on short pedicels; capsule oblong, 10-ribbed. — 

 Gravelly places in the Chattahoochee River, Nuttall. — Plant larger than the 

 last 



Order 119. EUPHORBIACE^. (Spurge Family.) 



Plants commonly vrith acrid milky juice, and monoecious or dioecious 

 often petalous flowers. — Calyx 2 — 8-lobed, mostly valvate in the bud, 

 sometimes wanting. Stigmas 2 - several, simple or divided. Fruit of 2 - 

 several (mostly 3) 1 - 2-seeded carpels united around a central axis, sep- 

 arating at matuirity, rarely 1 -colled or indehiscent. Seeds suspended, 

 anatropous. Embryo in fleshy albumen. Cotyledons flat. 



