438 MONOECIA POLYANDRIA. 



HAB. In water. Aug. Sept. 1].; stem slend., branch. ; leaves ver* 



ticil, by fours) finely pectin. 

 M. verticillatum : leaves pinnate, capillary, upper ones pectinate-pu> 



natifid ; flowers axillary, verticillate, upper ones sterile, octamlrous. 

 HAB In water. July, %\ floating ; upper fl. sometimes perfect. 



381. SAGITTARIA. Arrow-head. 



S. sagittifolia : leaves sagittate, acute ; lobes acute, straight, lanceo- 

 late. 



a. latifolia: leaves broad-ovate, rather obtuse; lobes ovate, slightly 

 acuminate, straight. 



b. hastata : leaves oblong-lanceolate, acute ; lobes spreading, lanceo- 

 late, long-acuminate ; flowers mostly dioecious. 



g. gracilis : leaves linear ; lobes much spreading, linear, very long and 

 acute. 



d. pubescent : leaves and stem pubescent ; bracts and calyx very pu- 

 bescent. 



HAB. Ponds, &c. July, TJ.; leaves large ; scape 1 2 ft. long ; Jl. 

 large, wh., verticil, in threes. 



S. obtusa : leaves- sagittate, dilated-ovate, rounded at the extremity, mu- 

 cronate; lobes approximate, oblong, obliquely acuminate, straight; 

 flowers dioecious ; sterile scape branched at the base. 



HAB. Ponds. July, Ij.; leaves large ; sap milky, affording gum ; 

 Jl.wh. 



S. heteropkylla : leaves simple, linear and lanceolate, acute at each ex- 

 tremity, or elliptical and sagittate, with the lobes linear and divari- 

 cate; scape simple, few-flowered; flowers monoecious, the fertile 

 subsessile. 



HAB. Ponds. July, If.; scape 1 ft. high ; leaves rarely sagitt. 



S. simplex : leaves linear-lanceolate, acute, narrowed towards the base; 

 scape simple, many-flowered ; flowers dioecious. 



HAB. Muddy banks, &c. Aug. 'ZJ. ; scape 8 15 in. high ; leaves 

 not rigid ; Jl. small. 



S. acutifolia: leaves subulate, sheathed at the base, convex on the 

 back ; scape simple, few-flowered, longer than the leaves ; flowers 

 monoecions. 



HAB. Muddy shores. Aug. 1\. ; scape 6 in. high ; flowers pedunc. ; 

 stam. 1315. 



382. QUERCUS. Oak. 



* Fructification biennial ; leaves setaceously mucronate. 



GL tinctoria: leaves ovate-oblong, slightly lobcd, pubescent beneath ; 



lobes oblong, obtuse, mucronate ; cup flat ; acorn depressed-globose. 

 HAB. Woods. A large tree ; bark rough, blackish. 

 GL. discolor : leaves oblong, pinnatifid-sinuate, pubescent beneath ; 



lobes oblong-dentate, setaceously mucronate ; cup turbinate, acorn 



ovate. 

 HAB. Upland forests. A large tree ; young leaves downy on both 



sides. 

 d. coccinea : leaves long-petiolate, oblong, deeply sinuate, smooth ; 



lobes divaricate, dentate, acute, setaceously mucronate ; cup turbinate, 



scaly ; acorn short-ovate. 



