RUBIACEAE 569 



A very localized species, whose distribution is not yet understood. 

 It has been referred to the western P. elongata Pursh. 



P. heterophylla Nutt. has been collected as a weed near Camden and Philadelphia. 

 P. Coronopus L. has been collected as a waif near Philadelphia and near New York. 



RUBIACEAE 



Leaves opposite, stipulate (sometimes verticillate in No. 3). 

 Ovules numerous in each cavity of the ovary; herbs. 



Top of the capsule free from the ovary; seeds few, peltate. I. Houstonia. 

 Capsule wholly adnatc to the ovary ; seeds minute, angular. 2. Oldenlandia. 

 Ovules I in each cavity of the ovary. 



Shrubs or small trees; flowers in dense globular heads. 3. Cephalanthus. 



Low evergreen herbs; flowers 2 together, with their ovaries 



united. 4. MlTCHELLA. 



Herbs; flowers axillary, nearly sessile, distinct. 5. Diodia. 



Leaves appearing verticillate; herbs. 



Corolla rotate; calyx-teeth .minute or none. 6. Galium. 



Corolla funnelform. 



Flowers in panicles. 7. Asperula. 



Flowers in involucrate heads. 8. Sherardia. 



i. Houstonia L. 



Plants 2.5-18 cm. high; peduncles i-flowered. 1. //. coerulea. 



PI, nils 10-25 cm. high; flowers cymose. 2. H. longifolia. 



1. H. coerulea L. In open grassy places, or on wet rocks: N. S. 



to One., Mich., Ga. and Ala. 



Conn. Throughout the state. 



N. Y. Reported from but not definitely known on L. I.; on S. I., 



rare in the Bronx, thence increasing northward. 

 N. J. Throughout the state except in the pine-barrens, and at 



Cape May; always increasing westward and northward. 

 Pa. Throughout the area. 



Tertiary, unknown on Beacon Hill, rare elsewhere: Cretaceous, 

 not common: Older Formations, increasing and becoming common 

 northward. 117-220 days. Sea level-4,020 ft. 



2. H. longifolia Gaertn. In dry open places: Me. and Ont. to 



Man., Ga. and Mo. 



Conn. Rare and local but scattered over most of the state, more 



common along the coast than elsewhere. 

 N. Y. Common on L. I., unknown on S. I., otherwise known 



only from a doubtful record in Greene Co. 



