190 LEMNACEvE. Lemna. 



seed orthotropoas, oblong, "vvith a prominent acute operculum. — Linnaea, xxxiii. 

 239; Hegelm. 1. c. 136, t. 7, fig. 1-8, and Fl. Bras. fasc. 76, t. 1, tig. iv. L. 

 Torreyi, Austin ; Gray, Manual, 479. 



In springs, Lake County {BolancUr) ; about San Francisco {Bolander, Kellogg & Harford) ; Los 

 Angeles {Brewer) ; Nortliern Nevada ( IFalson) ; Arizona {Palmer), and eastward to tlie Atlantic ; 

 also South American. 



3. L. minor, Linn. Fronds round- to elliptic-obovate, 1 to 2\ lines in diame- 

 ter, ratlier thick, very obscurely 3-nerved : bract sac-like : seed oblong-obovate, 

 amphitropous, with prominent rounded operculum. — Nees, Gen. iii. t. 42 ; Hegelm 

 L c. 112, t. 9, 10; Eeichenb. 1. c. 8, t. 14. 



Reported from various localities in Califoi'nia (Lobos Creek, Bolander, etc.), and common in all 

 f^uarters of the globe — the most widely distributed of all the species, and usually abundant, 

 closely covering the surface of stagnant pools. 



L. PAUCicosTATA, Hegelm., may perhaps also be found in California, resembling L. minor, but 

 with orthotropous seed, and the sheaths at the base of the young roots with broad wino--like 

 appendages ; bract reniforni ; frond with a minute dorsal spine near the apex. 



* * Ovules 2 to 7, anatropous : fronds very thick and spongy, fiat above, very 

 obscurely 5-7ierved. — Telmatophace, Hegebn. 



4. L. gibba, Linn. Fronds obovate-elliptic to nearly orbicular, almost hemi- 

 spherical, soon separating: bract sac-like. — Hegelm. 1. c. 145, t. 11-13; 

 lieichenb. 1. c. 



Near San Francisco {Bolander, in flower) ; Santa Barbara {Torrey) ; Arizona {Palmer) ; in the 

 Atlantic States, but rather rare ; in Mexico, the West Indies, and all quarters of the Old World. 

 A very peculiar and easily recognized species. 



2. SPEIRODELA, Schleiden. 

 Anther-cells bilocellate by a vertical partition and dehiscent longitudinally. Ovary 

 2-ovuled. Frond 7- 1 1 -nerved or more ; rootlets several, with axile vascular tissue. 

 Otherwise nearly as Lemna. — A single species. 



1. S. polyrrhiza, Schleid. Fronds round-obovate, purple beneath, 2 to 4 lines 

 in diameter, distinctly about 7-nerved ; roots clustered, usually 3 to 5 : bract sac- 

 like : ovules ampiiitropous. — Hegelm. 1. c. 147, t. 16, and Fl. Bras. 1. c. fig. vi. ; 

 Austin, Torr. Bot. Bull. i. 37, figs. ; Engelm. same, i. 42. Lemna 2iolyrrhiza, Linn. ; 

 lieichenb. 1. c, t. 15. 



Truckee River, Nevada ( JVatson) ; Oregon {Rail) ; and found in all quarters of the globe, 

 l)ut not yet reported from within the limits of California. It is very rarely detected in flower or 

 fruit, though often very abundant. 



Order CXIV. NAIADACE^. 



Marsh or mostly immersed aquatic herbs, with stems jointed and leafy or (in 



Triglochin) naked and scape-like, leaves sheathing at base or stipulate, and flowers 



perfect or unisexual, often spathaceous, with perianth of 4 or 6 herbaceous distinct 



valvate segments, or membranous and tubular or cup-shaped, or none; stamens 1, 



2, 4 or 6, with extrorse anthers ; ovaries 1 to 6, distinct or more or less coherent, 



1-celled, usually 1-ovuled, in fruit follicular or capsular or an indehiscent berry or 



utricle ; albumen none ; embryo large, often curved. 



An order (as here understood, embracing the Jnncaqinece) of about 20 genera and 70 or more 

 species, mdely distributed chiefly through temperate and cooler regions, both in fresh and saline 

 waters. There is much diver.sity in the characters of the genera. With few exceptions the 

 Cahtornian species are the same as those on the Atlantic coast, and are also found in the Ohl 

 World. 



