22 KEY TO THE SPECIES 



2. SILENE (Oatchfly) 



Herbs with solitary or clustered flowers, a 5-toothed calyx, 5 petals with slen- 

 der stalk-like base, 10 stamens, 3 styles, a 1-3-celled ovary, and a pod opening at 

 apex by 3 or 6 teeth. 



1. Silene antirrhina L. (Sleepy Oatchfly). A slender, nearly glabrous 

 annual, 3-5 dm. high, glutinous about the upper nodes ; leaves from spatulate 

 below to linear above ; inflorescence an open cyme, the pink flowers on slender 

 pedicels ; calyx narrowly ovoid ; petals obcordate, Common on dry sandy rocky 

 banks and slopes. 



3. VACCARIA 



A smooth glaucous annual herb, with tubular, angled, 5-toothed calyx, 5 

 petals, 10 stamens, 2 styles, and a pod which splits at summit into 4 teeth, 



1. Vaccaria Vaccaria (L.) Britt. (Cow Herb or Cockle). Erect, branching 

 above into the wide-spreading cyme ; leaves ovate to lanceolate, acute at apex and 

 clasping at base, 3-5 cm. long ; flowers small, white or rose color ; calyx inflated 

 in fruit. A common weed in cultivated grounds ; Introduced from Europe. 



4. CERASTIUM (Chickweed) 



Small pubescent herbs with weak stems, terminal cymes, white flowers having 

 5 sepals, 5 petals, 10 stamens, and 5 styles ; a cylindric capsule opening by 10 teeth. 



1. Cerastiuiu occidentale Greene (Western Chickweed). Tufted, with 

 many sterile leafy shoots from the base ; the numerous flowering stems somewhat 

 decumbent, 1-8 dm. long, few-leaved ; leaves broadly linear, acute ; cyme few to 

 several-flowered ; peduncle, pedicels and calyx glandular-pubescent ; sepals sea- 

 rious-margined, acute, about 5 mm. long ; petals and mature capsule about twice 

 as long as the sepals. Common on open slopes and in grassy draws. 



5. ARENARIA (Sandwort) 



Tufted herbs with slender sessile leaves, white flowers in cymes which are 

 either compact (head-like) or more open ; sepals and petals 5 ; styles 3 ; capsule 

 globose or oblong, many-seeded and opening by either 3 or 6 teeth. 



* Flowers in a close head. 



1. Arenaria congesta Nutt. (Congested Sandwort)." Many-stemmed 

 from the crown of a thick tap-root, smooth, 1-2 dm. high ; leaves subulate-linear, 

 pointed, scabrous on the margins ; flowers in 1-3 dense clusters, with large, dilated 

 membranous bracts ; petals nearly twice as long as the sepals. Frequent on open 

 or wooded slopes. 



* * Flowers in a more open cyme. 



2. Arenaria Fendleri Gray (Fendler's Sandwort). Similar to the preced- 

 ing in habit, glandular above, the leaves serrulate- scabrous ; flowers in an open 

 cyme, small ; sepals acuminate, about as long as the 6-7 mm. long, white, obovate 

 petals, scarious-margined ; seeds roughened. Dry open hillsides. 



3. Arenaria Hookeri Nutt. (Hooker''s Sandwort). A cespitose peren- 

 nial, the mats usually broad; leaves glabrous, crowded, stiff, awl-shaped and 

 sharp-pointed, 1-3 cm. long ; flowering stems short (5-10 cm.), pubescent ; cyme 

 crowded ; bracts linear-lanceolate, with ciliate margins, exceeding the similar 

 sepals ; petals twice as long as the sepals. Frequent on barren stony hills and 

 plains. 



