PODOSTEMACEJE. CrIVER-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. Itadicic long, superior. — 

 Consisting of the single genus 



1. CALLITRICHE, L. Wateb-Starwort. 



1. C. V3rna, L. Floating leaves spatulatc or obovate, crowded, the lower 

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

 liftoropliylla, Ell) — Var. TP:RUK'iTKis. Smaller (2' -3' long); stems much 

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

 and sliallow water, Fioriihi, and northward. March and April. — Stems several, 

 6' - 12' lung. Leaves ^' long. 



Order 118. PODOSTE3IACEiE. (River-weed Family.) 



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

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

 2-cellc(l. Capsule 2 - 3-celled, and pointed by as m:iny [)crs;stent 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 ovar}% united below, and bearing only a single anther. 

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

 Su!)merged aquatic plants, attached to rocks and pebbles by disk-like expan- 

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



1. P. ceratophyllum, Michx. Leaves rigid, sparingly divided, sheath- 

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

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

 1'- 4' long. 



2. P. abrotanoides, Nutt. Leaves much divided, with hair-like 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.i:. (Spurge Family.) 



Plants commonly with 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 maturity, rarely 1-celled or indehiscent. Seeds suspended, 

 anatropous. Embryo in fleshy albiunen. Cotyledons flat. 



