FLOKA OF THE DISTRICT OF COLUMBIA. 127 



1. Sisyrinchium mucronatum Michx. 



Meadows and fields; common north and west of Washington. May. Northeastern 

 U. S., south to Va. 

 Distinguished from the other species by its sessile spathes. 



2. Sisyrinchium intermedium Bicknell. 



Low wet soil along the Potomac and Rock Creek; rare. May. Central Atlantic 

 states. 



This doubtful species is included on Bicknell's identification. It is perhaps a 

 form of 5. mucronatum. 



3. Sisyrinchium gramineum Ciu-tis. 



Wet meadows and damp woods; frequent. May-June. Eastern U. S. {S. anceps 

 of Ward's Flora; S. graminoides Bicknell.) 



This species can be readily recognized by the black color it takes when wilted. 



4. Sisyrinchium atlanticum Bicknell. 



In or near marshes; common northeast of Washington. May-June. Atlantic 

 Coast Region. 



32. ORCHIDACEAE. Orchis Family. 



Inflorescence a spirally twisted spike. Flowers white or greenish white. 



9. IBIDIUM. 

 Inflorescence not spirally twisted. 

 Leaves not present (or if present much withered) at floAvering time. 



Roots coral-like; plants without green coloring matter; leaves reduced to brown- 

 ish sheaths 13. CORALLORRHIZA. 



Roots not coral-like; plants with green coloring matter, producing a leaf in the 



fall, this persisting throughout the winter, but usually withering before 



flowering time. 



Leaf plaited, green on both sides or sometimes purplish beneath near the base, 



turning brown in withering; scape bracted, purplish, appearing in May; 



lip not spurred 16. APLECTRUM. 



Leaf smooth, green above and purple beneath, turning bright scarlet in wither- 

 ing; scape bractless, straw-colored, appearing in July; lip spurred. 



17. TIPULARIA. 

 Leaves present (fresh and green) at flowering time. 

 Leaf only one (bract sometimes leaflikc in Pogonm). 

 Leaf elliptic or ovate, borne near the middle of the stem. 

 Flowers solitary, or rarely two, in the axil of a large bract, rosy pink or^white; 



plants growing in bogs 4. POGONIA. 



Flowers many, small, in a short raceme with minute bracts, greenishlyellow; 



plants growing in woods 14. MALAXIS. 



Leaf Linear-lanceolate, basal. 



Flower solitary; perianth segments close together, rosy purple; lip pendent; 



plant 15-30 cm. tall, flowering in May 8. ARETHUSA. 



Flowers several; perianth segments spreading, rosy pink; lip erect; plant 



20-45 cm. tall, flowering in July 7. LIMODORUM. 



Leaves more than one (rarely only one in Hahenaria and Orchis). 

 Stem leafy only at the base. 

 Flower solitary, large. Lip a moccasin-shaped sac, divided down the middle. 



1. CYPRIPEDIUM. 

 Flowers more than one. 



Inflorescence spikelike; lip saccate; leaves several, white-netted, thick, 

 remaining green through the winter. Flowers greenish white. 



11. PERAMIUM. 



