

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 alternate. 



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 perfect.or if monoecious or dioecious, not in capitate clusters. 

 Flowers regular. 



Carpels several or numerous, or if solitary becoming an achene. 

 Carpels distinct, 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. 

 Ovarv with several ovules : leaf-blades 2-3- pinnate : fruit! a 



legume. 



Petals valvate in the bud. Fam. 15. MIMOSACEAE. 



Petals imbricated in the bud, Gl-editsia and Gymnocladu* 



in CASSIACEAE. Fam. 16. CASSIACEAE. 



Flowers irregular (nearly or quite regular in Gleditsia and Gym- 

 nocladu* 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 enclosed by the lateral ones in the bud. Fam. 16. CASSIACEA:. 



Upper petal enclosing the lateral ones in the bud. Fam. 18. FABACEAE. 



FAMILY 1. PODOSTEMACEAE Lindl. RIVER-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. FODOSTEMON 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. 



Flower solitary : capsules oval. 8-ribbed : leaf-segments flattened. 1. P. CeratophyUum. 



Flowers 2 or 3 together : capsules oblong. 10-ribbed : leaf-segments almost capillary. 2. P. abrotanoides. 



1. Podostemon CeratophyUum 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. 



In running water, on rocks, Ontario to Minnesota, New York, Georgia, Alabama and Kentucky. 

 Summer and fall. 



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. 



