498 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Corolla large, blue, purple, or white, the tube 

 much shorter than the calyx; stamens re- 

 curved 2. Eustoma (p. 499). 



Styles stout and short or none; stamens straight. 

 Corolla with nectariferous glands, pits, or scales. 

 Corolla campanulate; flowers yellow; low 



annual 3. Halenia (p. 499). 



Corolla rotate; flowers yellow or blue; per- 

 ennials. 

 Style manifest; leaves verticillate ; co- 

 rolla with a crown at the base 4. Frasera (p. 499). 



Style wanting; leaves opposite, occa- 

 sionally alternate; corolla without 



a crown 5. Swertia (p. 500). 



Corolla without nectariferous glands, pits, or 

 scales. 

 Calyx parted to near the base; corolla rotate 

 or nearly so; stamens inserted on the 



base of the corolla 10. Pleurogyna (p. 503). 



Calyx merely lobed; corolla not rotate; 

 stamens inserted in the corolla tube. 

 Corolla without plaits or lobes at the 

 sinuses; calyx without an inter- 

 calycine membrane; sepals im- 

 bricated. 

 Flowers 4-merous, rather large, us- 

 ually over 3 cm. long; corolla 

 lobes fringed or toothed; in- 

 ner sepals broader, mem- 

 branous-margined 6. Anthopogon (p. 501). 



Flowers 5-merous (seldom 4-merous), 

 small, less than 2 cm. long; 

 outer sepals broader; corolla 

 lobes never fringed, rarely 



toothed 7. Amarella (p. 501). 



Corolla plicate in the sinuses, the plaits 

 more or less extended into mem- 

 branous lobes or teeth; calyx with , 

 an intercalycine membrane, its 

 lobes valvate. 

 Dwarf annuals or biennials; flowers 

 solitary, terminal; anthers cor- 

 date, versatile 8. Chondropttylla (p. 502). 



Perennials; flowers short-peduncu- 

 late, at least some of them 

 axillary; anthers linear or ob- 

 long, extrorse 9. Dasystephana (p. 502). 



1. CENTAURIUM Hill. Centaury. 



Low branched annuals with bright rose pink flowers; calyx 4 or 5-parted, with 

 slender keeled divisions; corolla salverform, with 4 or 5 lobes; stamens 4 or 5, 

 partly adnate to the corolla tube; anthers twisted at maturity; ovary 1-celled; stig- 

 mas 2; capsule 2-valved, oblong. 



