ROBINSON. — ALSINE^E. 275 



11. Arenaria. Sepals 5. Petals as many, white or nearly so, 

 entire or emarginate (very rarely minute or wanting). Stamens 10, 

 or often fewer by abortion. Styles 3 or 4. Seeds many. 



++ -M- Styles as many as the sepals and alternate with them. 



12. Sagina. Sepals 5, (rarely 4). Petals as many, entire or 

 emarginate, white, rarely obsolete. Stamens usually 5, less frequently 

 3-10. Valves of the capsule as many as the sepals, and opposite 

 them. Seeds several to many. 



* * Stipules present, scarious : petals undivided. 



13. Spergularia. Sepals 5. Petals 5 (rarely fewer or none), 

 reddish or white. Stamens commonly 10. Styles 3 (very rarely 5) ; 

 ovary 1-celled ; valves of the capsule as many as the styles, when 5 

 in number alternate with the sepals. Seeds often margined. Leaves 

 linear or filiform. 



14. Spergula. Sepals 5. Petals 5. Stamens 10 (rarely 5). 

 Styles 5 ; ovary unilocular, many-ovuled. Valves of the capsule 5, 

 opposite the sepals. Seeds acutely margined or narrowly winged. 

 Leaves narrow, linear, verticillate and fascicled in the axils. 



Tribe III. POLYCARPE^E. Including genera 15-18. (See 

 Proc. Am. Acad, xxviii. 126.) 



8. HOLOSTEUM, L. (6'Aos, all, and 6ar iov, bone ; used iron- 

 ically, since the plants are soft and weak.) — A small genus of Old 

 World annuals and biennials much resembling Cerastium except 

 in inflorescence and seeds. The commonest species is adventive in 

 America. — Gen. no. 928; Reichb. Icon. Fl. Germ. v. t. 221; Gay, 

 Ann. Sci. Nat. ser. 3, iv. 23 ; Benth. & Hook. Gen. i. 148. 



H. umbellatdm, L. Finely glandular-pubescent, somewhat glau- 

 cous : stems 3-18 inches high : leaves sessile, ovate-oblong : umbels 

 3-12-flowered, terminal upon long naked peduncles; pedicels 8-12 

 lines long, some of them reflexed : filaments shorter than the calyx. — 

 Spec. 88 ; Eng. Bot. i. 27. Locally naturalized in Pennsylvania, 

 New Jersey, and Delaware, Porter, Austin, Canby, Small. (Adv. 

 from Eur.) 



9. CERASTIUM, L. Mouse-ear Chickweed. (iclpas, a 

 horn, from the elongated curved capsules.) — Annuals or perennials, 

 usually pubescent and often viscid. Leaves usually flat. Flowers 

 white, borne in more or less expanded leafy or naked cymes. A genus 

 distinguished from Stellaria and Arenaria somewhat by habit, but 

 chiefly, although not always satisfactorily, by the form and dehiscence 



