FLOEA OF THE DISTRICT OF COLUMBIA. 153 



4. Alsine media L. Common chickweed. 



Common nearly everywhere in damp ground. Feb.-May. Native of Eur. and Asia; 

 naturalized nearly throughout N. Amer. {Stellaria media Cyrillo.) 



The plants may be found in flower at almost any time during the winter if there are 

 a few warm days. Stellaria neglecta Weihe {S. media procera Klett & Richter) is a 

 form with 10 stamens and somewhat crested seeds. It has been reported from our 

 region by Holm. 



Alsine aquatica (L.) Britton, with 5 styles and large leaves, was collected along the 

 Pennsylvania Railroad, southeast of H Street Bridge, July, 1915 (/. B. S. Norton). 

 Native of Eur.; sparingly adventive in N. Amer. (Stellaria aquatica Scop.) 



5. ARENARIA L. 

 1. Arenaria serpyllifolia L. Sandwort, 



Common nearly everywhere. Apr.-June. Naturalized from Eur. nearly through- 

 out eastern N. Amer. ' 



6. SAGINA L. Pearlwort. 



Parts of the flower in 5's; seeds orange-brown, resinous-dotted 1. S. decumbens. 



Parts of the flower in 4's; seeds dark brown, not resinous-dotted. . .2. S. procumbens. 



1. Sagina decumbens (Ell.) Torr. & Gray. 



About Washington; rare. May-June. Eastern U. S. (S. apetala of American 

 authors.) 



2. Sagina procumbens L. 



Ammendale (Brother Arsene); brick walk in front of Army Medical Museum 

 (Maxon & Standley). Apr. -May. Eastern U. S. 



54. SILEFACEAE. Pink Family. 



Calyx with twice as many ribs or nerves as teeth. 

 Lobes of the calyx as long as the tube or often much longer; petals much shorter 



than the calyx lobes, purple 1. AGROSTEMMA. 



Lobes of the calyx much shorter than the tube; petals usually much longer than 

 the calyx lobes, or rarely wanting. 



Styles 3 or rarely 4 2. SILENE. 



Styles 5 .' 3. LYCHNIS. 



Calyx with 5 nei"ves or ribs, or nerveless, or with very nmnerous nerves (more than 

 twice as many as the teeth). 

 Plants more or less hairy, especially about the flowers; leaves linear; calyx finely 



many-nerved, bracted at the base 4. DIANTHTJS. 



Plants perfectly glabrous; leaves much broader than linear; calyx not bracted at 

 the base. 

 Calyx sharply 5-angled; pedicels usually much longer than the calyx; leaves 



sessile and clasping 5. VACCARIA. 



Calyx not angled; pedicels much shorter than the calyx; at least the lower 

 leaves short-petioled 6. SAPONARIA. 



1. AGROSTEMMA L. 



1. Agrostemma githago L. Corn cockle. 



Frequent in fields and waste ground. May-July. Native of Eur. and northern 

 Asia; naturalized in grain fields nearly throughout the U. S. (Lychnis githago Scop.) 



The seeds are poisonous. 



2. SILENE L. 



Leaves in whorls of 4, ovate-lanceolate, long-acuminate. Stems finely hairy; calyx 

 inflated; petals white 1. S. stellata. 



