2955] 



REVISION OF THE GENUS SAGITTARIA 



213 



The var. chapmani of Florida, Georgia, and Alabama is easily recognized by 

 its elongate bracts, branching scapes, and small receptacles and achenes. Its 

 mode of branching at times resembles that of some species of Alisma and Echi- 

 nodorusy in that as many as five whorls may have the pedicels replaced by 

 branches. 



The var. macrocarpa of the Carolinas is distinguished mainly by the large, 

 crenate-crested achenes and, to a lesser degree, by the spatulate leaf-shape. 



The var. cristata of the northwestern Great Lakes region has a geographic 

 distribution approaching that of a subspecies, for it has in large measure replaced 

 var. graminea throughout its range. The short, basal phyllodia in association 

 with the long-petioled, small-bladed emersed leaves, the large, crested achenes, 

 and the filaments longer than the anthers are all distinctive. 



The other previously proposed species here included in synonymy are probably 

 ecological forms of 5". graminea. They include the small, sterile, phyllodial plants 

 of eastern, tidal waters (5. eatoni); the husky southern plants with horizontal 

 rhizomes (S. cycloptera); the plants with tapering, terete phyllodes of southern 

 lakes having a marked seasonal drop of water level (S. isoetijormis) and the 

 elongate phyllodial plants of moving waters (S. edwardsiana). Another plant limited 

 to the Cumberland plateau of northeastern Alabama is worthy of mention, although 

 it has never been separated from S. graminea. It is unique in having elongate 

 rhizomes that produce a series of phyllodia along their entire length in contrast 

 to the typical apical crown of leaves. In general it resembles other flowing-water 

 forms of S. graminea and pending further study has not been separated from that 

 species. S. lancifolia var. angustifolia of Grisebach is based on mixed collections 

 of Wright in Cuba and in large part must be considered as S. graminea^ although 

 it is included in the synonymy of S. lancifolia as well. 



11. Sagittaria lancifolia L. Syst. Nat. ed. 10. 2: 1270. 1759. 



Perennial with well-developed rhizomes. Leaves typically emersed with linear 

 to ovate or elliptical blades 12-35 x 0.7-19 cm, the rare submerged leaves modi- 

 fied into stiff, terete phyllodia to 50 cm long, the petioles to 100 cm long. Scape 

 overtopping the leaves, 40-210 cm long, simple with 5-12 whorls of flowers or 

 frequently branching at the lowest whorl. Bracts thickened, more or less joined 

 at the base, striate to papillose, elongate, 0.5-3.5 cm long. Pedicels ascending, 

 1-5 cm long. Sepals reflexed, striate to papillose, 0.5-1 cm long; petals white, 

 about twice as long as the sepals. Stamens large and numerous, the linear pubes- 

 cent filaments 1.5-5 mm long, the oblong anthers 1-2.7 mm long. Mature receptacle 

 1-1.8 cm in diameter; achenes narrowly obovate to falcate, 1.5-2.3 x 0.8-1.2 mm, 

 the dorsal wings 0.3-0.4 mm wide, occasionally somewhat inflated, the ventral 

 wings 0.15 mm or less wide, the faces with 0-2 low wings or rarely with a resin 

 duct, the obliquely inserted, thick-based beaks 0.3-0.7 mm long. 



1. Bracts and sepals more or less striate-ribbed; plants of South America, 



West Indies, and peninsular Florida. 11a. subsp. lancifolia. 



1. Bracts and sepals more or less papillose; plants of Central America, and 



the coastal plain regions of Mexico and eastern United States. lib. subsp. media. 



Explanation of Figure 11 



FIG. 11. Distribution of the varieties of S. graminea. a-c, var. platypbylla. a, achene, 

 X 3. b, bracts, X %. c, stamen, X 3. d-f, var. teres, d, achene, X 3. e, bracts, X 1. f, 

 stamen, X 3. g-i, var. weatherbiana. g, achene, X 3. h, bracts, X 7 / 3 . i, stamen, X 3. j-1, 

 var. cristata. achene, X 3. k, bracts, X%» 1, stamen, X 3. m, n, var. chapmani. m, achene, 

 X 3. n, bracts, X %. o, var. macrocarpa t achene, X 3. 



