402 Obdeb 67.— RUBIACBA 



6. DIO^DIA L. (Gr. dig, twice, dSovg, tooth, alludjng to the two 

 calyx teeth crowning the ovary.) Calyx, corolla, stamens, style and 

 fruit as in the next genus (Spermacoce) except that the (2 or 3) 1-seeded, 

 separable carpels are in both indehiscent ; seeds oval, peltate. — American, 

 chieifly tropical herbs. Stip. fringed with bristles. Fls. small, white, 

 axillary, sessile, solitary or few. 



1 D. Virgini^na L. Procumbent, nearly glabrous or hirsute ; sis. squarish ; Ivs- 

 lanceolate, sessQe, entire ; bristles of the stip. longer than the sheaths ; iis. soli- 

 tary, opposite ; cor. salver form, tube very slender, thrice larger than the cal. ; 

 atam. exserted ; style deeply 2 -cleft, lobes filiform. — 1( Damp places, HI. to Ga. 

 and La. St. 1 to 2f long, somewhat 4-3ided. Lvs. 1 to 2' by 3 to 5", 1-veined, 

 often with smaller ones fascicled in the axils. Cor. 6" long, hairy inside. May — 

 September. 



li. has ovate-lanceolate lvs. (D. tetragona "Walt.) 



y. has lance-linear, hairy lvs. ; cor. 6" long. May — Sept. (D. hirsuta Ph.) 



2 D. teres "Walt. Erect or ascending, hairy or scabrous ; lvs. hnear-lanoeojate, 

 sessile, rough-edged, acute, much longer than the sheaths or fruit ; fls. solitary, or 

 several in each axil ; cor. funnel-fnrm, with a wide tube, twice longer them the cat. ; 

 fl. somewhat hairy and 4-sided. — Sandy fields, N. J. to lU. (Mead) and S. States. 

 Sts. rather rigid, simple, or branched, 5 to 18' long, brownish. Lvs. about 1' by 

 2". Cor. reddish white, shorter than the reddish brown bristles. Aug., Sept. 

 (Spermacoce diodina Mx.) 



7. SPERMACO'CE, L. (Gr. ampfia, seed, aKUKfj, a point ; alluding 

 to the pointed seeds.) Calyx tube ovoid, limb 2 to 4-parted ; corolla 

 tubular, limb spreading, 4-lobed ; stamens 4 ; stigma 2-cleft ; fruit dry, 

 2-cellod, crowned with the calyx, separating into 1 open and 1 indehis- 

 cent carpel ; seeds 2, peltate, furrowed on the face. — Mostly herbaceous 

 and tropical. Fls. small, in dense, axillary, sessile whorls, or clusters. 



1 S. glabra Mx. Glabrous, procumbent at base ; lvs. lanceolate, entire ; whorls 

 many-flowered ; cal. 4-toothed (rarely 5) ; cor. funnel-form, short, hairy in the 

 throat ; anth. included in tho tube ; stig. subaessile. If Eiver banks, "W. States. 

 St. 1 to 2f long, terete, with 4 prominent lines, branched. Lvs. 2 to 3' by i to 1'', 

 tapering to each end. Pis. white, 9 to 20 in a whorl, subtended by the subulate 

 bracts of the stipules. Jl., Aug. — Resembles some of the Labiatse. 



2 S. Chapmdnii Torr. & Gr. Nearly glabrous ; st. slightly 4-angled ; lvs. ob- 

 long-lanceolate, attenuate to a petiole ; whorls dense-flowered ; cor. funnel-form, 

 thrice longer than the cal. ; stam. and slender sty. exserted. — Biver banks, Mid- 

 Fla. (Chapman.) 



8. HOUSTO'NIA, L. Bluets. (Dedicated to Dr. Wm. Houston, 

 the friend and correspondent of Miller.) Calyx tube ovoid-globous, 

 limb 4-toothed or cleft, persistent ; corolla tubular, much exceeding the 

 calyx ; limb 4-lobed, spreading ; filaments 4, inserted on the corolla ; 

 style 1 ; anthers and stigmas dimorphous, that is, in some plants, the 

 former exserted and the latter included, in others the style exserted and 

 anthers included ; capsule 2-lobed, the upper half free, cells few (8 to 

 20)-seeded. — Herbs. Stip. connate with the petiole, entire. Fls. soli- 

 tary or in cymes, white, purplish, or bluish. 



§ Corolla salver-form, glabrous. PeJanoles 1-flowered— terminal Nos. 1, 2 



—axillary •''"It*' « 



§ Corolla funnel-form. Peaunolos CD -flowered, cymovis. — Leaves lanoe-ovate No. 5 



— Leaves lance-linear Nos. 6, 7 



1 H. ooerilea L. Dwaef Pink. Innocbsoe. Coespitous ; radicai bis. ovate- 

 spaiulaite, petiolate ; sts. erect, numerous, dichotomous ; ped. filiform, 1 to 2-flow- 

 ered. — @ An elegant little plant found in moist grounds, fields, and road-sides, 

 Canada and TJ. S., often ia patches. Caultne lvs. very small, opposite, lance- 



