PONTEDERIACE^". (PICKEREL-WEED FAMILY.) 4S3 



- - Head single (or sometimes 2 or 3) : leaves channelled above : stamens 6. 



15. J. Stygius, L. Stem slender, erect (6' -10' high), l-3-leaved below, 

 naked above ; leaves thread-like ; heads 3 - 4-flowered, about the length of the 

 sheathing scarious awl-pointed bract; sepals oblong and lanceolate, scarcely 

 more than half the length of the oblong acute pod ; seeds oblong, with a very 

 loose coat prolonged at both ends. Peat-bog bordering Perch Lake, Jefferson 

 County, New York. (Eu.) 



16. J. trifidlis, L. Stems densely tufted from matted creeping rootstocks, 

 erect (5' -10' high), wiry and thread-like, sheathed at the base, leafless below, about 

 3-leaved at the summit ; the upper thread-like leaves subtending the sessile head 

 of 2 - 4 flowers ; sepals ovate or oblong, acute, rather than the globose-ovate 

 beak-pointed (brown) pod; seeds roundish, angled. Alpine summits of the 

 mountains of N. New England and N. New York, and high northward. (Eu.) 

 "*--- Flowers cymose-panided, separate (not clustered in heads) : leaves channelled 



or involute, or else thread-form, or almost setaceous : stamens 6. 



17. J. tennis, Willd. Stems slender, wiry (9' -18' high), simple, leafy 

 only near the base ; cyme shorter than the involucral leaves, small, the flowers 

 mostly one-sided, almo'st sessile, green and shining ; sepals lanceolate, very acute, 

 one third longer than the globose-ovoid obtuse pod. Low grounds and fields ; very 

 common. 



18. J. Greenii, Oakes & Tuckerm. Stems rigid (l-2 high), simple, 

 naked, 1 - 2-leaved at the base ; cyme much shorter than the principal erect involucral 

 leaf, dense, the numerous crowded flowers one-sided ; sepals lanceolate, acute, 

 greenish, shorter than the ovoid-oblong obtuse pod. Sandy coast of Long Island 

 and New England, and occasionally on river-banks in the interior. 



19. J. blllbosns, L. (BLACK GRASS.) Stems simple, somewhat fattened, 

 slender, but rigid (l-2 high), leafy below; panicle somewhat cymose, rather 

 crowded, usually shorter than the bracteal leaf; sepals oval-oblong, obtuse, incurved, 

 chestnut-color and greenish, mostly rather shorter than the oblong-oval and 

 somewhat triangular obtuse mucronate pod. (J. compressus, Jacq. : a name 

 with which some supersede the Linnsean, because the stem is really not bulbous 

 at the base.) Var. GERARDI (J. Gerardi, Loisel., and J. Bothnicus, Wahl.) is 

 the more common form in this country, with the panicle usually exceeding the 

 bract, and the calyx as long as the pod. Salt marshes ; common along tho 

 coast from New Jersey northward. (Eu.) 



20. J. bllfonillS, L. Annual; stems low and slender (3' -9' high), leafy, 

 often branched at the base ; panicle forking, spreading ; the flowers remote, greenish ; 

 sepals lanceolate, awl-pointed, much longer than the oblong obtuse pod. Low 

 grounds and road-sides, everywhere. (Eu.) 



ORDER 129. PONTEDERIACE^G. (PICKEREL-WEED FAM.) 



Aquatic herbs, with perfect more or less irregular flowers from a spathe ; 

 the petal-like Q-merous perianth free from the 3-celled ovary; the 3 or 6 most- 

 ly unequal or dissimilar stamens inserted in its throat. Perianth with the 6 



