PODOSTEMACEAE 495 
** Carpels fewer than the sepals. . ; : 
Staminodia present: carpels 3 or 4, wholly united into a 1-celled gynoecium. 
Fam. 4. PARNASSIACEAE. 
Staminodia wanting}: carpels mostly 2, distinct or partially 
united. Fam. 5. SAXIFRAGACEAE. 
b. Shrubs or trees. 
Leaves opposite. Fam. 6. ESCALLONIACEAE. 
Leaves Pi T per 
Fruit a 2-celled capsule. 
Capsule thin-walled, almost free from the hypanthium. Fam. 7. ITEACEAE, 
Capsule woody or thick-walled, manifestly adnate to the 
hypanthium. Fam. 8. ALTINGIACEAE. 
Fruit a 1-celled berry. Fam.’ 9. GROSSULARIACEAE. 
B. Endosperm wanting or scant (copious in Opulaster in ROSACEAE): 
stipules mostly present. 
Flowers monoecious, in dense capitate clusters. Fam. 10. PLATANACEAE. 
Flowers perfeet,orif monoeciousor dioecious,not in capitate clusters. 
Flowers regular. 
Carpels several or numerous, or if solitary becoming an achene. 
Carpels distinet, rarely adnate to the hypanthium: fruit 
achenes or follicles. 
Sepals and petals 5: leaves mostly alternate. Fam. 11. ROSACEAE. 
Sepals and petals numerous: leaves opposite. Fam. 12. CALYCANTHACEAE. 
Carpels united, enclosed by the hypanthium and adnate to : 
it : fruit a pome. Fam. 13. MALACEAE. 
Carpel solitary, not becoming an achene. 
Ovary with 2 ovules: leaf-blades simple: fruit a drupe. Fam. 14. AMYGDALACEAE. 
Ovary with several ovules: leaf-blades 2-3-pinnate: fruitia 
legume. 
Petals valvate in the bud. Fam. 15. MIMOSACEAE. 
Petals imbricated in the bud, Gleditsia and Gymnocladus 
in CASSIACEAE. Fam. 16. CASSIACEAE. 
Flowers irregular (nearly or quite regular in Gleditsia and Gym- 
nocladus in CASSIACEAE.) 
Fruit indehiscent, armed with barbed spines: leaf-blades|sim- 
_ple: stipules wanting. Fam. 17. KRAMERIACEAE. 
Fruit a legume or loment: leaf-blades compound: stipules 
usually present. 
Upper petal enelosed by the lateral] ones in the bud. Fam. 16. CASSIACEAE. 
Upper petal enclosing the lateral ones in the bud. Fam. 18. FABACEAE. 
FAMILY 1. PODOSTEMACEAE Lindl. RrvER-WEED FAMILY. 
Annual aquatic herbs, with poorly differentiated vegetative organs, com- 
monly resembling the thallus of an alga or hepatic. Leaves alternate: blades 
often divided. Flowers usually perfect, incomplete, subtended by a spathe-like 
involucre. Perianth wanting, or when present of 3-5 membranous sepals. An- 
droecium of 2 or sometimes many hypogynous stamens. Anthers 2-celled, open- 
ing lengthwise. Gynoecium of 2 or 3 united carpels. Ovary 2-3-celled. Styles 
2 or 3, short. Ovules several or numerous, anatropous. Fruit a 2-3-celled rib- 
bed capsule. Seeds often numerous. Endosperm wanting. Embryo straight. 
1. PODOSTEMON Michx. 
Fresh-water caulescent herbs, various in habit, usually resembling algae. Leaves al- 
ternate : blades divided or dissected. Flowers inconspicuous, sessile or nearly so in the 
spathe-like involucre. Perianth wanting. Stamens 2: filaments united to near the top. 
Staminodia 2, slender. Ovary 2-celled. Stigmas 2, narrow, nearly erect. Capsule lon- 
ger than thick, 2-valved, 6-10-ribbed. Seeds very small. 
NET: capele oval. 8-ribbed : leaf-segments flattened. ; 1. P. Ceratophyllum. 
er: capsules oblong, 10-ribbed : leaf-segments almost capillary. 2. P. abrotanoides. 
1. Podostemon Ceratophyllum Michx. Plants olive green, glabrous. Stems 0.5-2 
dm. long, attached to stones in running water by disk-like expansions: leaves rigid ; 
blades divided into many narrow segments, the base sheathing the stem : flowers solitary, 
slender-pedicelled, about 1.5 mm. broad, bursting from the spathes : united filaments much 
onger than the ovary : capsules oval, 2.5 mm. long, obtuse at both ends, 8-ribbed. 
id ser Bine WMer, on rocks, Ontario to Minnesota, New York, Georgia, Alabama and Kentucky. 
2. Podostemon abrotanoides Nutt. Similar to the preceding species in habit, but 
larger, the stems sometimes becoming 6 or 7 dm. long. Leaves often numerous : blades 
much divided into almost capillary segments : flowers 2 or 3 together, short-pedicelled : 
capsules oblong, 10-ribbed. 
On gravelly river bottoms, Georgia and Florida to Mississippi. Summer. 
