. ■ - 



FLORA OF THE DISTRICT OF COLUMBIA. 65 



2. .LOPHOTOCABPTJS T. Durand. 



1. Lophotocarpus calycinus (Engelm.) J. G. Smith. 



Apparently rare; collected only by Steele in the "Eastern Branch below the Navy 

 Yard, growing in tide mud;" reported as growing "below Alexandria." Sept. 

 Southern states, north to Del. 



3. SAGITTARIA L. Arrowhead. 



Leaves linear to elliptic or ovate (plants rarely with one or more hastate leaves in 

 S. rigida). 

 Leaves usually 3-10 (sometimes 20) cm. long; filaments glabrous; plants dwarfish. 



Beak of the achene erect or nearly so • 1- s - subulata. 



Leaves 12-25 cm. long; filaments glandular-pubescent; plants larger. 

 Bracts acute, 3-6 mm. long, united to the middle or beyond; beak of the achene 



horizontal, very short 2. S. graminea. 



Bracts obtuse, 4-8 mm. long, united at the base or sometimes distinct; beak of the 

 achene erect or nearly so, about one-fourth the length of the body. 



3. S. rigida. 



Leaves arrow-shaped. 

 Lobes of the leaves very narrowly linear (1-3 mm. wide). Beak of the achene erect. 



4. S. engelmanniana. 



Lobes of the leaves broader (at least 7 mm. and often 90-120 mm. wide). 

 Bracts and pedicels pubescent. Beak of the achene horizontal ... 5. S. pubescens. 

 Bracts and pedicels glabrous. 

 Fertile pedicels much longer than the broadly triangular, obtuse, acute, or 

 occasionally acuminate bracts; beak of the achene horizontal. 



6. S. latifolia. 



Fertile pedicels shorter than the triangular-lanceolate acuminate bracts; beak 

 of the achene nearly erect ?• S. longirostra. 



1. Sagittaria subulata (L.) Buchenau. 



Tide-water mud along the Potomac and Eastern Branch; common. July-Sept, 

 N.Y. toFla. (S. pusilla Nutt.) 



2. Sagittaria graminea Michx. 



In the same localities as the preceding species. July-Sept. Eastern N. Amer. 



3. Sagittaria rigida Pursh. 



Swamps and shallow water; probably common throughout the region. July- 

 Sept. Eastern states, south to Md. (S. heterophylla Pursh.) 



4. Sagittaria engelmanniana J. G. Smith. 



Collected only by Steele, who says: "First collected, in sterile condition only, in 

 a swampy pasture near Ardwick, Md., September 6, 1899. Two or three fruiting 

 specimens were found on the water's edge at Great Falls, October 3, 1899. 

 Determination confirmed by Mr. J. G. Smith." Mass. to Va. 



5. Sagittaria pubescens Muhl. 



Common in shallow water, ditches, and swamps. July-Sept. Eastern states, 

 south to Va. ($. latifolia pubescens J. G. Smith.) 



6. Sagittaria latifolia Willd . . 



Common in habitats similar to those given for the preceding species. July-hept. 

 General in N. Amer. except the subarctic zone. (S. variabilis Engelm.; 8. variabilis 

 angustifolia A. Gray.) 



7. Sagittaria longirostra (Micheli) J. G. Smith. „„ 11+v 

 Collected only by Steele, "in moderate quantity in the marsh around the mouth 



of Oxon Run, opposite Alexandria. August 38, 1900." Southern states, north toN. J. 



69289—19 5 



