LOASACE^E. (LOASA FAMILY.) 135 



up # # Stamens 4 : petals rather persistent : carpels even on the back : leaves chiefly 

 scattered, or wanting on the flowering stems. 



5. M. ambiguum, Nutt. Immersed leaves pinnately parted into about 

 10 very delicate capillary divisions ; the emerging ones pectinate, or the upper floral 

 linear and sparingly toothed or entire ; flowers mostly perfect; fruit (minute) 

 smooth. Var. 1. NATANS : stems floating, prolonged. Var. 2. CAPILLA- 

 CEUM : steins floating, long and very slender ; leaves all immersed and capil- 

 lary. Var. 3. LIM6SUM : small, rooting in the mud; leaves all linear, incised, 

 toothed, or entire. Ponds and ditches, Massachusetts to New Jersey, Penn., 

 and southward, near the coast. July - Sept. 



6. M. tciiclllllll, Bigelow. Flowering stems nearly leafless and scape-like, 

 (3' -10' high), erect, simple; the sterile shoots creeping and tufted; bracts 

 small, entire ; flowers alternate, monoecious ; fruit smooth. Borders of ponds, N. 

 New York, New England, and northward. July. 



9. HIPPURIS, L. MARE'S-TAIL. 



Calyx entire. Petals none. Stamen 1, "inserted on the edge of the calyx, 

 Style single, thread-shaped, stigmatic down one side, received in the groove be- 

 tween the lobes of the large anther. Fruit nut-like, 1 -celled, 1 -seeded. Peren- 

 nial aquatics, with simple entire leaves in whorls, and minute flowers sessile in 

 the axils, perfect or polygamous. (Name from irnros, a horse, and ovpd, a tail.) 



1. II* vulgftiris, L. Leaves in whorls of 8 or 12, linear, acute. Ponds 

 and springs, New York to Kentucky and northward: rare. Stems simple, 1- 

 9 high. Flowers very inconspicuous. (Eu.) 



ORDER 44. LOASACEyE. (LOASA FAMILY.) 



Herbs, with a rough or stinging pubescence, no stipules, the calyx-tube ad- 

 herent to a 1-celled ovary with 2 or 3 parietal placentae : represented only 

 by the genus 



1. UIENTZEL.IA, Plum. (BART6NIA, Nutt.) 



Calyx-tube cylindrical or club-shaped ; the limb 5-parted, persistent. Petals 

 5 or 10, regular, spreading, flat, convolute in the bud, deciduous. Stamens in- 

 definite, rarely few, inserted with the petals on the throat of the calyx. S:;- 1 s 

 3, more or less united into one : stigmas terminal, minute. Pod at length dry 

 and opening irregularly, few -many-seeded. Seeds flat, anatropous, with little 

 albumen. Stems erect. Leaves alternate. Flowers terminal, solitary or 

 cymose-clustered. (Dedicated to C. Mentzel, an early German botanist.) 



1. IH. OligOSpermsi, Niitt. Rough and adhesive (1- 3 high), much 

 branched, the brittle branches spreading ; leaves ovate and oblong, cut-toothed 

 or angled ; flowers yellow (7'' -10" broad), opening in sunshine; petals wedge- 

 oblong, pointed ; stamens 20 or more : filaments filiform : pod small, about 9- 

 (D U Prairies and plains, Illinois and southw ffitrward. 



