PONDWEED FAMILY. 29 



5. P. pectinatus L. Fennel Pondweed. Stems % or 2 to several feet 

 long, arising from a running rootstock, repeatedly forking above, then very 

 leafy and forming broom-like clusters; leaves setaceous, 1 to 3 in. long exclu- 

 sive of the sheaths which are V- 2 to % in. long or on the lower leaves even 

 2 in. long; searious margin of the sheaths very narrow; spikes y> to 1\ 2 in. 

 long, the flowers in distinctly separated whorls; peduncles 1 to 3 or more in. 

 long; nutlet I 1 /* to 2 lines long, Avith an obscure ridge on each side of the 

 back. 



The most common species throughout California from sea-level to 7000 ft. 

 alt., species of world-wide distribution. The rootstocks imbedded in the mud of 

 ponds bear tubers about the size of a pea. The deep-diving ducks, such as 

 the Canvas-back and Broad-bill feed upon these sweet, nutritious tubers, pull- 

 ing loose at the same time more or less of the tender rootstocks and the 

 attached stems which float to the surface and are shared with the surface- 

 feeding species like the Teal and Mallard. It is to this plant that the Canvas- 

 back, while living in the salt-marshes, owes the succulent and nutty flavor of its 

 flesh, making it in the eyes of sportsman and epicure superior to every 

 other kind of wild-fowl. 



6. P. latifolius Morong. Near the preceding; stems stoutish, white, branch- 

 ing; leaves numerous, fascicled terminally, V- 2 to lV-y lines broad; adnate portion 

 of stipule % to 1 in. long, broad on the uppermost leaves, scarious-margined, 

 the free portion shorter. 



Brackish water: Gilroy; Amedee, Lassen Co., Davy, to Oregon. 



2. RUPPIA L. Ditch-grass. 



Immersed aquatic herbs with long filiform forking stems. Leaves almost 

 capillary, with a broad membranous sheathing base. Peduncles slender, 

 axillary, at first very short and enclosed in the spathe-like base of the leaf, 

 each bearing two flowers disposed near together and rising to the surface in the 

 period of anthesis, afterwards coiling and drawing the fruits beneath the 

 water. Flowers perfect, entirely destitute of perianth. Stamens 2, sessile, 

 each anther consisting of 2 large and separate anther-cells. Pistils 4, after 

 flowering becoming stalked; stigmas depressed, sessile. (H. B. Euppius, a 

 German botanist of the 18th century.) 



1. R. maritima L. Ditcii-grass. Plants 2 to 3 ft. long; leaves 2 to 3 in. 

 long; pistils ripening into hard ovoid nuts, which at maturity are 74 to 1 ] 4 

 lines long, and raised on stipes 1 to 12 lines long; fruiting peduncle 3 to lines 

 long. 



Alkaline or brackish waters: Southern California northward through the 

 State. Cosmopolitan. 



3. NAIAS L. Naiad. 



Slender branching submerged fresh-water plants with linear opposite spiny- 

 toothed leaves, which are seemingly whorled on account of the ones crowded in 

 the axils. Flowers unisexual, solitary in the axils. Staminate flower consist- 

 ing of a single stamen enclosed by two perianth like envelopes. Pistillate flower 

 3ting of a single ovary bearing a style with 2 to 4 Btigmas. Fruit a 

 seed-like nutlet, tipped with the persistent style. (Greek Xnins, n water- 

 nymph.) 



Leaves coarsely toothed, the sheathing base entire or with 1 or 2 teeth on each 



sirle ' 1- -\ • marina. 



Leaves very minutely serrulate. 



Nutlet shining, smooth; sheathing base of leaves with many minute teeth on it:-, 

 upper portion 2. .V. flcxilis. 



