PODOSTEMACEAE 



495 



**Carpels fewer than the sepals. 



Staminodia present: carpels 3 or 4, wholly united 



into a 1-celled gynoecium. 

 Staminodia wanting: carpels mostly 2, distinct or 



partially united, 

 b. Shrubs or trees. 

 Leaves opposite. 

 Leaves alternate. 



Fruit a 2-celled capsule. 



Capsule thin-walled, almost free from the hypan- 



thium. 



Stamens 5: hypanthium flattish, not accres- 

 cent: leaves without stipules. 

 Stamens numerous: hypanthium hemispheric, 

 inflated in age: leaves with stipules. Opu- 

 laster in 

 Capsule woody or thick-walled, manifestly adnate 



to the hypanthium. 

 Calyx, or calyx and corolla, present: ovule 



solitary in each carpel, suspended. 

 Calyx and corolla wanting: oyules several or 



numerous in each carpel, horizontal. 

 Fruit a 1-celled berry. 

 B. Endosperm wanting or scant (copious in Opulaster in Ro- 



SACEAE) : stipules mostly present. 

 Flowers monoecious, in dense capitate clusters. 

 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. 

 Sepals and petals numerous: leaves opposite. 

 Carpels united, enclosed by the hypanthium and 



adnate to it: fruit a pome. 

 Carpel solitary, not becoming an achene. 



Ovary with 2 ovules: leaf -blades simple: fruit a 



drupe. 

 Ovary with several ovules: leaf -blades 2-3-pinnate: 



fruit a legume. 

 Petals yalvate in the bud. 

 Petals imbricated in the bud, Gleditsia and 



Gymnocladus in CASSIACEAE. 

 Flowers irregular (nearly or quite regular in Gleditsia 



and Gymnocladus in CASSIACEAE). 



Fruit indehiscent, armed with barbed spines: leaf- 

 blades simple: stipules wanting. 

 Fruit a legume or loment: leaf -blades compound: 



stipules usually present. 



Upper petal enclosed by the lateral ones in the bud. 

 Upper petal enclosing the lateral ones in the bud. 



Fam. 4. PARNASSIACEAE. 

 Fam. 5. SAXIFRAGACEAE. 

 Fam. 6. HYDRANGEACEAE. 



Fam. 7. ITEACEAE. 

 Fam. 11. ROSACEAE. 



Fam. 8. HAMAMELIDACEAE. 



Fam. 8a. ALTINGIACEAE. 

 Fam. 9. GROSSULARIACEAE. 



Fam. 10. PLATANACEAE. 



Fam. 11. ROSACEAE. 



Fam. 12. CALYCANTHACEAE. 



Fam. 13. MALACEAE. 



Fam. 14. AMYGDALACEAE. 



Fam. 15. MIMOSACEAE. 

 Fam. 16. CASSIACEAE. 



Fam. 17. KRAMER: ACEAE. 



Fam. 16. CASSIACEAE. 

 Fam. 18. FAB ACEAE. 



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. PODOSTEMON Michx. 



Fresh-water caulescent herbs, various in habit, usually resembling algae. Leaves 

 alternate: 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 longer than thick, 2-valved, 6-10-ribbed. Seeds very small. BIVER-WEED. 



Flower solitary: leaves short; segments flattened. 



Flowers 2 or 3 together: leaves elongated: segments almost capillary. 



1. P. Ceratophyllum. 



2. P. abrotanoides . 



