Vol.. II. ] 



WATER-MILFOIL FAMILY. 



501 



Calyx-tube adnate to the ovar}', its limb entire or 2-4-lobed. Petals small, 

 2-4, or none. Stamens 1-8. Ovary ovoid-oblong, or short-cylindric, 2-8-ribbed 

 or winged, i-4-celled; styles 1-4; stigmas papillose or plumose. Fruit a nutlet, 

 or drupe, compressed, angular, ribbed or winged, indehiscent, of 2-4 i-seeded 

 carpels. Endosperm fleshy; cotyledons minute. 



Eight genera and about 100 species, of wide geographic distribution. 



Stamen i; ovary i -celled. i. Hippuris. 



Stamens 2-8; ovary 3~4-celled. 



Fruit 3-angled or 4-angled. 2. Proserpinaca. 



Fruit of 4 carpels. 3. Myriophyllum. 



i. HIPPURIS L. Sp. PI. 4. 1753. 



Aquatic herbs, with simple erect stems, and verticillate simple entire leaves. Flowers 

 small, axillary, perfect, or sometimes neutral or pistillate only. Limb of the calyx minute, 

 entire. Petals none. Stamen i, inserted on the margin of the calyx. Style filiform, stig- 

 matic its whole length, lying in a groove of the anther. Fruit a small i-celled i-seeded 

 drupe. [Greek, mare's-tail.] 



Three known species, natives of the north temperate and arctic zone and of southern South 

 America. Besides the 2 following, the third occurs in northwestern arctic America. 



Leaves linear or lanceolate, in verticils of 5-12. 



Leaves obovate, oblong, or oblanceolate, in verticils of 4-6. 



1. H. vulgaris. 



2. H. tetraphylla. 



i. Hippuris vulgaris L,. Bottle Brush. 

 Mare's-tail. Joint-weed. (Fig. 2613.) 



Hippuris vulgaris L. Sp. PI. 4. 1753. 



Stem slender, glabrous, 8 / -2O / high. Leaves linear 

 or lanceolate, acute, sessile, J"-I2" long, i // -2 // wide, 

 in crowded verticils of 6-12, more or less sphacelate at 

 the apex; stamen with a short thick filament, and com- 

 paratively large 2-celled anther, dehiscent by lateral slits; 

 seeds ovoid, hollow in the interior; stigma persistent. 



Swamps and bogs, Labrador and Greenland to Alaska, south 

 to Maine, the shores of Lake Superior, and in the Rocky 

 Mountains to New Mexico, and on the Pacific Coast to Cali- 

 fornia. Also in Patagonia, and in Europe and Asia. Summer. 

 English names, Cat's-tail, Paddock-pipes, Knotgrass. 



2. Hippuris tetraphylla L,.f. Four-leaved Mare's- 

 tail. (Fig. 2614.) 



Hippuris tetraphylla L. f. Suppl. 81. 1781. 



Hippuris maritime, Hell. Dissert. Hippur. pi. i. 1786. 



Smaller than the preceding species. Stem 4 / -i5 / high; 

 leaves obovate or oblanceolate, entire, in verticils of 4-6, not 

 sphacelate at the apex or but slightly so, 4 // ~7 // long. 



Labrador and Quebec to Hudson Bay and Alaska. Also in north- 

 ern Europe and Asia. Summer. 



2. PROSERPINACA L. Sp. PI. 88. 1753. 



Aquatic herbs, with simple stems decumbent at the base. Leaves alternate, lanceolate, 

 dentate or pectinate-pinnatifid. Flowers perfect. Tube of the calyx adnate to the trique- 

 trous ovary, the limb 3~4-parted. Petals none. Stamens 3-4. Styles 3-4, cylindric or 

 conic-subulate, stigmatic above the middle. Fruit bony, 3-4-angled, 3-4-celled, with i seed 

 in each cavity. [Middle Latin, for ward -creeping.] 



Two known species, natives of eastern North America, extending to the West Indies. 



