( 325 ) 
1. L. supuLata HBK.—San Francisco. 
School House Station. Searsville. Spring. 
2. Zostera L. EEu-Grass. 
Flowers monecious. Spathe elongated into 
a lamina. Spadix flattened, dorsally naked, 
ventrally covered by alternate stamens and 
ovaries arranged in two rows. Anthers 1-celled, 
sessile. Ovary rostrate. Style persistent.— 
2¢. Stems and roots submerged. 
1. Z. marina L.—Brackish inlets around the 
bay. Summer. . 
The bulbous root is edible, and is eagerly 
sought for by the canvas-back duck. 
Family 2, LEMNACEA. 
Aquatic plants without axis. Flowers en- 
closed in a thin membranaceous spathe. Sta- 
mens 1 or 2. Ovary sessile, l-celled; ovules 
1-6; style short. Fruit a utricle. 
1. Lemna L. DUCKWEED. 
Stamens 2. 
1. L. reisutca L. Ovule solitary; fronds 
oblong, stalked, remaining connected.—Presi- 
dio. Autumn. 
2. L. Vauprviana Philippi. Ovule solitary; 
fronds notstalked, soon separating; bract reni- 
form.—Marine Hospital. Autumn. 
