666 FLORA. 



diate flowers often perfect. Lower flowers pistillate, the calyx 4-grooved and with 

 4 minute lobes, or none; ovary 2-4-celled; ovule I in each cavity, pendulous; styles 

 4, short, often plumose. Fruit splitting into 4 bony I -seeded indehiscent carpels. 

 [Greek, myriad-leaved.] About 20 species, of wide distribution. In addition to 

 the following, another occurs in the western U. S. The plants flower in summer. 



Carpels smooth. 



Flowers in emersed spikes. 



Floral leaves shorter than the flowers. 



Flowers in whorls. i. M. spicatum. 



Flowers alternate, or the lower sub-verticillate. 3. M. alterniflorum. 

 Floral leaves longer than the flowers, pinnatifid. 2. M. vertictllatum. 



Floral leaves reduced to minute bracts. 4. M. tencllum. 



Flowers on both emersed and submersed stems. 5. M. humile. 



Flowers only on submersed stems. 9. M. proserpinacoides. 



Carpels rough or tuberculate. 

 Flowers on emersed spikes. 



Floral leaves ovate or lanceolate, serrate. 6. M. heterophyllum. 



Floral leaves linear, pectinate. 7. M. pinnatum. 



Flowers on submersed stems. 8. M. Farwellii. 



1. Myriophyllum spicatum L. SPIKED WATER-MILFOIL. (I. F. f. 2617.) 

 Submerged leaves in whorls of 4*5 and 5's, dissected into capillary division?. 

 Floral leaves ovate, or sometimes none ; spike 2-8 cm. long ; petals 4, deciduous ; 

 stamens 8; fruit about 2 mm. long and 3 mm. thick; carpels rounded on the back, 

 with a deep wide groove between them. In deep water, Newf. to the N. W. Terr., 

 Fla., Iowa, Kans. and Cal. Also in Europe and Asia. 



2. Myriophyllum verticillatum L. WHORLED WATER-MILFOIL. (I. F. f. 

 2618.) Submerged leaves in crowded whorls of 3*5 and 4's, the capillary divisions 

 very slender, often minutely scabrate. Floral leaves much longer than the flowers ; 

 spike 5-15 cm. long; petals of the staminate flowers 4. purplish; stamens 8; fruit 

 2-3 mm. long, and about 2 mm. thick, somewhat gibbous at the base. Quebec 

 and Ont. to Fla., Minn, and Cal. Also in Europe and Asia. 



3. Myriophyllum alterniflorum DC. LOOSE-FLOWERED WATER-MILFOIL. 

 (I. F. f. 2619.) Submerged leaves usually in whorls of 3's to 5's, occasionally scat- 

 tered, the pinnate divisions capillary. Spikes short, 2-5 cm. long; uppermost floral 

 leaves ovate or linear, entire or minutely toothed, early deciduous; petals of the 

 staminate flowers 4, longer than the stamens, pale rose-color, deciduous; stamens 

 8; fruit nearly 2 mm. long, slightly less than 2 mm. thick; carpels rounded on the 

 back, with a deep groove between them. In deep water, eastern Mass, to Newf. 

 and Greenland. Common in Europe. 



4. Myriophyllum tenellum Bigel. SLENDER WATER-MILFOIL. (I. F. & 

 2620.) Stems slender, scape-like, nearly leafless, 4-30 cm. high. Rhizome creep- 

 ing, sending up many sterile stems; flowers alternate, solitary; uppermost bracts 

 obovate, often longer than the flowers, the lower oblong, often shorter, the lowest 

 minute or none; petals 4, purplish; stamens 4; fruit I mm. long and about as 

 thick at the top, sometimes enlarged at the base; carpels rounded or obtusely 

 angled on the back, separated by a shallow groove. Sandy bottoms of ponds and 

 streams. Newf. to N. J., Penn. and Mich. 



5. Myriophyllum humile (Raf.) Morong. Low WATER-MILFOIL. (I. F. f. 

 2621.) Typical form terrestrial, 2-4 cm. high, rooting in mud. Leaves entire or 

 pectinate. Floating forms with stems often 3 dm. long, with all or most of the 

 leaves pectinate; these produce the typical form if they take root; petals 4, pur- 

 plish; stamens 4; fruit usually less than 2 mm. long and about as thick at base, its 

 carpels separated by a shallow groove. In ponds, Me., R. L, to Md. and 111. 



6. Myriophyllum heterophyllum Michx. VARIOUS-LEAVED WATER-MIL- 

 FOIL. (I. F. f. 2622.) Floral leaves in whorls of 3*5 to 5's. linear, ovate or lan- 

 ceolate, serrate or rarely entire, much longer than the flowers. Submerged leaves 

 subverticillate or scattered, crowded, pectinate-pinnatifid, about 2 cm. long, the 

 divisions capillary; flowering spike elongated; petals 4; stamens 4, rarely 6; fruit 

 2 mm. long, and slightly longer than thick; carpels 2-keeled on the back. In 

 ponds, Ont. and N. Y. to Fla., S. Dak., Tex. and Mex. 



7. Myriophyllum pinnatura (Walt.) B.S.P. PINNATE WATER-MILFOIL. 



