212 



RUBIACEAE. 



[Vol. III. 



Houstonia. 

 Oldenlandia. 



Cephalanthus. 

 Mitchella. 



5. Spermacoce. 



6. Diodia. 



7. Galium. 



8. Sherardia. 



9. Aspertila. 



1. /f. coerulea. 



2. //. serpyllifolia. 



About 355 genera and 5500 species of very wide geographic distribution, most abundant in 

 tropical regions. Known as Madderworts. 



-"- 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. 

 Capsule wholly adnate to the ovary; seeds minute, angular. 

 Ovules 1 in each cavity of the ovary. 



Shrubs; flowers in dense globular heads. 



Low evergreen herbs; flowers 2 together, their ovaries united. 

 Herbs; flowers axillary, nearly sessile, distinct. 

 Capsule separating into 2 dehiscent carpels. 

 Capsule separating into 2 (or 3) indehiscent carpels. 

 & -$f Leaves appearing verticillate; herbs (some of the leaves rarely opposite in No. 7) 



Corolla rotate; calyx teeth minute or none. 

 Corolla funnelform. 



Flowers in involucrate heads. 



Flowers in panicles. 



i. HOUSTONIA L,. Sp. PI. 105. 1753. 



Erect or diffuse, usually tufted herbs, with opposite entire often ciliate leaves, and small 

 blue purple or white, mostly dimorphous flowers. Calyx-tube globose or ovoid, 4-lobed, the 

 lobes distant. Corolla funnelform or salverform, 4-lobed, the lobes valvate, the throat gla- 

 brous or pubescent. Stamens 4, inserted on the tube or throat of the corolla; anthers linear 

 or oblong. Ovary 2-celled. Style slender; ovules numerous in each cavity; stigmas 2, linear. 

 Capsule partly inferior, its summit free from the calyx, globose-didymous, or emarginate 

 at the apex, loculicidally dehiscent above. Seeds few or several in each cavity, peltate, 

 more or less concave, not angled. Seed-coat reticulate or roughened; endosperm horny; 

 embryo club-shaped. [Named in honor of Dr. William Houston, botanist and collector in 

 South America, died 1733.] 



About 25 species, natives of North America and Mexico. 



5 Plants i'-7' high ; peduncles i-flowered. 

 t Peduncles filiform, i'-2^' long. 

 Erect; leaves obovate or spatulate, narrowed into petioles. 

 Diffuse or spreading; leaves nearly orbicular. 



f f Peduncles 3"-i8" long, stouter. 



Calyx-lobes narrow, about equalling the capsule. 

 Calyx-lobes broad, much exceeding the capsule. 



Sf -X- Plants 4'-i8' high ; flowers cymose. 

 Leaves broad, ovate, or ovate -lanceolate. 

 Leaves oblong or spatulate, ciliate. 

 Leaves linear-lanceolate or oblanceolate, not ciliate. 

 Leaves filiform or narrowly linear. 



Flowers loosely cymose on filiform pedicels ; leaves not fascicled. 



Flowers densely cyniose on very short pedicels; leaves usually fascicled 



i. Houstonia coerulea L,. Bluets. Innocence. (Fi 



Houstonia coerulea L. Sp. PI. 105. 1753. 

 Hedyolis coerulea Hook. Fl. Bor. Am. 1: 286. 



1833. 

 Oldenlandia coerulea A. Gray, Man. Ed. 2, 



174. 1856. 



Erect, 3 / -7 / high, glabrous, or nearly so, 

 perennial by slender rootstocks and form- 

 ing dense tufts. Lower and basal leaves 

 spatulate or oblanceolate, about 6" long; 

 sometimes hirsute or ciliate, narrowed 

 into a petiole, the upper oblong, sessile; 

 flowers solitary on filiform terminal and 

 axillary peduncles; corolla salverform, 

 violet, blue, or white with a yellow center, 

 4 // -6 // broad, its tube slender and about 

 the length of the lobes; capsule didy- 

 mous, compressed, about 2 // broad and 

 broader than long, the upper half free 

 from the calyx and shorter than its lobes. 



In open grassy places, or on wet rocks, 

 Nova Scotia to Quebec, New York and 

 Michigan, south to Georgia and Alabama. 

 April-July, or producing a few flowers 

 through the summer. Called also Quaker 

 Ladies, Quaker bonnets, Venus' Pride. 



3- 

 4- 



5- 

 6. 



7- 



lg- 



H. minor. 

 II. minima. 



H. purpurea. 

 H. ciliolata. 

 H. longifolia. 



H. tenuifolia. 

 H. angustifolia. 



3393-) 



