HA L OR A GIDA CEA E. 665 



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 

 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. 



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. Style filiform, stigmatic 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 zones 

 and of southern S. Am. Besides the following, the third occurs in arctic America. 



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



Leaves obovate, oblong, or oblanceolate, in verticils of 4-6. 2. H. tetraphylla. 



1. Hippuris vulgaris L. BOTTLE BRUSH. MARE'S-TAIL. JOINT-WEED. 

 (T. F. f. 2613.) Stem glabrous, 2-5 dm. high. Leaves acute, sessile, 1-25 mm. 

 long, more or less sphacelate at the apex ; stamen with a short thick filament, and 

 comparatively large 2-celled anther, dehiscent by lateral slits; seeds ovoid; stigma 

 persistent. Swamps and bogs, Greenland to Alaska, Me., Lake Superior, N. Mex. 

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



2. Hippuris tetraphylla L.f. FOUR-LEAVED MARE'S-TAIL. (I. F. f. 2614.) 

 Stem 1-4 dm. high; leaves not sphacelate at the apex or but slightly so, 8-14 mm. 

 long. Lab. and Quebec to Hudson Bay and Alaska. Also in northern Europe 

 and Asia. Summer. 



2. PROSERPINACA L, 



Aquatic herbs, with simple stems. Leaves alternate, lanceolate, dentate or 

 pectinate-pinnatifid. Flowers perfect. Tube of the calyx adnate to the triquetrous 

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

 dric or conic-subulate, stigmatic above the middle. Fruit bony, 3 4-celled, with 

 i seed in each cavity. [Middle Latin, forward-creeping.] Two known species, 

 natives of eastern N. Am., extending to the W. I. 



Emersed leaves linear-lanceolate to oblong, serrate; fruit sharp-angled, r. P. palustrts. 

 Leaves all pectinate-pinnatifid ; fruit obtusely angled. 2. P. pectinata, 



1. Proserpinaca palustris L. MERMAID-WEED. (I. F. f. 2615.) Glabrous, 

 simple or sometimes branched. 2-5 dm. long. Emersed leaves, 2-5 cm. long, 2-12 

 mm. wide, sharply serrate, the submerged ones pectinate-pinnatifid into stiff linear 

 acute segments which are often serrulate, bearing a minute black spine in their 

 axils; flowers solitary or several together, sessile in the axils of the emersed leaves; 

 fruit about 4 mm. long, the faces concave, smooth or rugose. In swamps, N. B. to 

 Lake Huron, Fla., Iowa and Cent. Am. Also in Cuba. July. 



2. Proserpinaca pectinata Lam. CUT-LEAVED MERMAID-WEED. (I. F. 

 f. 2616.) Resembling the preceding, but usually smaller. Leaves all pectinate or 

 pinnatifid, the segments shorter and rarely serrulate, more subulate, or capillary; 

 calyx-lobes broader; fruit about 3 mm. long, the faces flat or slightly convex, often 

 wrinkled or somewhat tuberculate, the angles obtuse. In sandy swamps near the 

 coast, eastern Mass, to Fla. and La. Summer. 



3. MYRIOPHYLLUM L. 



Aquatic herbs, with verticillate or alternate leaves, the submerged ones pin- 

 natirid into capillary segments, and axillary commonly monoecious 2-bracted 

 flowers, often interruptedly spicate. Upper flowers generally staminate with a very 

 short calyx-tube, its limb 2-4-lobed, or none; petals 2-4; stamens 4-8. Interme- 



