MYRIOPHYLLUM. LV. ONAGRACE^E. 267 



delicate plant, common in wet, rocky woodlands in mountainous districts, N. 

 Eng., Brit. Am. W. to Or. Stem diaphanous, juicy, 5 10' high. Leaves 1 

 2' long, as wide, acute or acuminate, with small, remote teeth, pale green and 

 shining. Flowers white, rarely reddish, minute, in terminal racemes. Jl. 



SUBORDER, H ALiORAGEJE. 



Plants small, aquatic. Flowers minute, axillary, sessile. Calyx entire, or 

 3 t-lobed. Petals 3 4, often 0. Stamens 1 8, inserted with the petals into 

 the summit of the calyx. Ovary inferior, 1 4-celled. Fruit dry, indehiscent, 

 1 4-celled. Seed pendulous, 1 in each cell. 



8. PROSERPINACA. 



Lat. Proserpina, a Roman goddess ; from some fancied resemblance. 



Calyx tube adherent to the ovary, 3-sided, limb 3-parted ; petals 

 ; stamens 3 ; stigmas 3 ; fruit 3-angled, 3-celled, bony, crowned 

 with the permanent calyx. 1|- Aquatic. Lvs. alternate. 



1. P. PALUSTRIS. Spear-leaved Mermaid-weed. 



'Livs. linear-lanceolate, sharply serrate above the water, those below (if 

 any) pinnatifid. Ditches, swamps and ponds, often partly submersed, N. Eng. ! 

 to Ark. Root creeping. Stems ascending at base, 6 20"' high, striate, round- 

 ish. Leaves 10 15" by 2 3", acute at each end, lower ones on short petioles, 

 and if growing in water, pinnatifid with linear segments. Flowers greenish, 

 sessile, 1 3 together in the axils of the upper leaves, succeeded by a very hard, 

 triangular nut. Jn. Jl. 



2. P. PECTINACEA. Lam. (P. palustris, 0. MX.) Cut-leaved Mermaid-weed. 

 Las. all pectinate, with linear-subulate segments ; fr. obtusely 3-angled. 



Sandy swamps, in Ms. ! (rare) S. to Flor. Stems 5 10' high, ascending at 

 base from long, creeping roots. Leaves all finely and regularly divided into 

 very narrow segments. Styles 0. Stigmas attenuate above. Fruit rather 

 smaller (less than I" diam.) than in P. palustris, rugose when mature. Jl. Aug. 



9. MYRIOPHYLLUM. Vaill. 



Gr. pvpios, a myriad, <f>v\\ov, a leaf; from the numerous divisions of the leaf- 



Flowers c? , or frequently $ ; calyx 4-toothed in the $ and 9 , 4- 

 parted in the c? ; petals 4, often inconspicuous or ; stamens 4 -8 ; 

 stigmas 4, pubescent, sessile ; fruit of 4 nut-like carpels cohering by 

 their inner angles. % Submersed, aquatic herbs. Submersed Ivs. parted 

 into capillary segments. Upper fis. usually cT, middle ones $, lower $. 



1. M. SPICATUM. Spiked Water-Milfoil. 



Lies, in verticils of 3s, all pinnately parted into capillary segments ; fls. 

 in terminal, nearly naked spikes ; floral Ivs. or bracts ovate, entire, shorter than 

 the flowers ; lowest ones subserrate and larger; pet. broadly ovate ; sta. 8; carpels 

 Smooth. N. Eng. to Ark., in deep water, the flowers only rising above the sur- 

 face. Stems slender, branched, very long. Leaves composed of innumerable, 

 hair-like segments, always submerged. Flowers greenish, sessile. Jl. Aug. 



2. M. VERTICILLATCM. Water- Mil foil. 



Lvs. in verticils of 3s, lower ones pinnately parted into opposite, capillary 

 or setaceous segments : fls. in terminal, leafy spikes ; floral Ivs. pectinate-pin- 

 natifid, much longer than the flowers; pet. oblong-obovate ; sta. 8; carpels 

 smooth. In stagnant water, Can. to Flor. W. to Oregon. Stem long, less slen- 

 der than in the last, only the upper part emerging. Flowers small, green, ax- 

 illary, with conspicuous floral leaves. Sepals acute. Anthers oblong. Jl. Aug. 



3. M. HETEROPHYLLUM. Mickx. (Potamogeton verticillatum. Walt.) 

 Lvs. in verticils of 5s, the lower ones pinnately parted into capillary 



lobes ; spikes terminal, nearly naked ; floral Ivs. ovate-lanceolate, serrate, longer 

 than the flowers, crowded; pet. oblong; sta. 4 r6; carpels scabrous, with 2 slight 

 ridges on the back. In sluggish water. Can. to Flor. and Tex., rare. Stem 

 23* 



