16 Holm Additions to the Flora of Washington. 



768. Polygonum hydropiperoides Michx. 



Old creek-bottom near Marshall Hall. 

 *778. Polygonum cristatum Engelm. 



Rocks near Great Falls, Md.; thickets near Hyattsville; common near 

 Seven Locks. With flower and fruit third week of September. 

 788. Aristolochia Serpentaria L. 



Abundant in ravines near Marshall Hall; ravines at Sligo avenue and 

 Rappley road near Takoma. 

 796^. Euphorbia hirsuta Wieg. 



Rocks at Great Falls, Md.; woods near Marshall Hall. 



800. Euphorbia commutata Eng. 



Common in rocky woods from Sandy Landing to Great Falls. 



801. Phyllanthus Carolinensis Walt. 



Old river bottom near Hyattsville; not uncommon in the woods at 

 Great Falls, Md. ; woods near Marshall Hall. 



812. Urtica dioica L. 



Not common. Along the tow-path near Great Falls. 



830. Corylus Americana Walt. 



Abundant near Sligo; South Brookland near the railroad track. 



849. Quercus heterophylla Michx. 

 Several trees, but all sterile, were found in the woods at Marshall Hall. 



901. Habenaria tridentata Hook. 



Woods near Great Falls, Md.; very abundant in swamps near Suratts- 

 ville. 



903. Habenaria ciliaris R. Br. 



Swamp near Bladensburg turnpike, south of the Reform School. G. 

 W. Oliver. 



904. Habenaria lacera R. Br. 



Swamp near the Reform School; several places in Brookland; Terra 

 Cotta swamp; swamps near Marshall Hall. 



909. Spiranthes gracilis Big. 

 Woods along Scott's Run, Va. 



910. Spiranthes simplex Gr. 



Woods near Great Falls, Md.; Terra Cotta; Brookland. 



912. Pogonia verticillata Nutt. 



Swamp near Bladensburg. Thos. H. Kearney, Jr. Abundant on the 

 sand hills around Fort Totten; damp woods near the Reform School; 

 swamps near Surrattsville. 



913. Calopogon pulchellus R. Br. 



Deanwood swamp. Thos. H. Kearney, Jr. Swamp near Surattsville. 



915. Microstylis ophioglossoides Nutt. 



Woods near Marshall Hall: woods near Great Falls, Md. 



