FLORA OF THE DISTRICT OF COLUMBIA. 155 



5. VAC C ARIA Medic. 



1. Vaccaria vulgaris Host. Cowherb. 



Occasional about Washington and Rosslyn. Adventive from Eur. in many parts 

 of the U. S. (Saponaria vaccaria L.; V. vaccaria Britton.) 



6. SAPONARIA L. 



1. Saponaria officinalis L. Bouncing bet. 



Common in waste ground and along roadsides. June-Oct. Native of Eur.; widely 

 naturalized in the U. S. 



The flowers are often double; they vary in color from almost white to deep pink. 



55. BTYMPHAEACEAE. Waterlily Family. 



Petals very small and thick, green; sepals much larger than the petals, green, tinged 

 with yellow; fruit naked; leaves usually longer than broad, green. 



1. NYMPHAEA. 



Totals large and showy, whije or pinkish; sepals equaling or shorter than the petals, 

 green; fruit covered wilh the bases of the petals; leaves as broad as long, purple 

 beneath 2. C ASTALIA. 



1. NYMPHAEA L. 



1. Nymphaea advena Soland. Yellow fondlilt. 



Shallow water or marshes; comm >n. May-Sept. Northern states, south to N. C. 

 (Nuphar advena Ait.) 



A colony of plants is shown i T ; plate 24. 



2. C ASTALIA Salisb. 



1. Castalia odorata (Dryand.) Woo lv. & Wood. White waterlily. 



Floating in water, Fourmile R- u. Laurel, near Alexandria, and probably elsewhere; 

 formerly found in pools at (irer.1 Falls. June-July. Eastern N. Amer. (Nymphaea 

 odorata Ait.) 



56. CABD^ISiCEAE. Water-shield Family. 



Leaves mostly dissected into numerous capillary lobes; stamens 3-6.. 1. CABOMBA. 

 Leaves oval, the petiole attached to the middle of the blade; stamens 12-48. 



2. BRASENIA. 

 1. CABOMBA Aubl. 



1. Cabomba ciroliniana A. Gray. 



Well established formerly in the fishponds in Potomac Park, but these have been 

 filled and the plants destroyed; reported by Steele from the Eastern Branch. 

 Southeastern U. S. 



Sometimes known as Washington plant. 



2. BRASENIA Schreb. 

 1. Brasenia schreberi Gmel. Water-shield. 



Edges of pools along the Potomac near Little Falls; Laurel; rare. June-July. 

 Eastern N. Amer. and on the Pacific coast; also Cuba and Mex. (B. peltata Pursh.) 



57. CERATOPHYLLACEAE. Hornwort Family. 

 1. CERATOPHYLLUM L. Hornwort. 



1. Ceratophyllum demersum L. 



Ponds and sluggish streams near the Potomac from Plummers Island southward; 

 frequent. Throughout the U. S. 



Readily propagating by buds; rarely fruiting. 



