178 EUBI.UEAK 



oylindric : flowers siibdioecious : capsule 2-seeded. — Coiumoii in dry 

 grounds and waste places. April-June. 



7. P. elongata Pursh. Puberulent annual, l'-4' high : spikes 

 slender: flowers subdioecious : stamens only two: capsule 4-8eeded. — 

 Locally common on sterile prairies from Lee's Summit to Greenwood, 

 and in dry woods near Grain Valley. April-Maj*. 



Family 118. RUBIACEAE P.. Juss. 

 Plants with opposite or verticillate usually stipulate leaves and per- 

 fect, regular, nearly symmetrical flowers. Calyx coherent with the 1-10- 

 celled ovarj'. Corolla gamopetalous, 4-5-lobed, variously shaped. Stamens 

 inserted on the corolla and alternate with its lobes. Ovules 1-many in 

 each cell of the ovary. Fruit various. 



Leaves opposite. 



Herbs : ovary with many ovules. 1. HousTONlA. 



Shrubs. ' 2. C'EPnALANTHUS. 



Herbs : ovary with two ovules. 3. DiODlA. 



Leaves verticillate. 4. (iALiuM. 



1. HOUSTONIA L. 



Calyx tube 4 lobed. Corolla funnel-form t»r salver form, 4-lobed. 

 Stamens four. Style one. Stigmas two. Upper half of the 8-40-seeded 

 capsule fiee from the calyx. Flowers dimorphous. 



1. H. minima Beck. Bluets. Annual, spreading, 2'-.5' high, sca- 

 brous : leaves oblong-oval, short-petioled : corolla purplish. — On prairies 

 and in dry woods, Little Blue Tank, Lee's Summit, Greenwood, Grain 

 Valley. April. 



2. CEPHALANTHUS L. 



Flowers white, in dense spherical heads. Calyx limb 4-lobed. Corolla 

 funnel-form, shortly 4-lobed. Stamens four, short. Styles one. Stigmas 

 two. Fruit dry, obpyramidal, 1-2-seeded. 



1. C. occidentalis L. BUTTOX Busii. 3°-l5° high : leaves ovate, 

 petioled entire: heads V in diameter. — Swampy grounds throughout. 

 Locally common. June-August. 



3. DIODIA L. 



Herbs with conspicuous stipules and small axillary flowers. Calyx 

 limb 4 lobed (in ours). Corolla funnel-form or salver-form, 4-lobed. 

 Stamens four. Fruit of two indehiscent 1-seeded carpels- 



1. D. teres Walt. Buttowveed. Annual, erect, spreading, 3'-15' 

 high, rough: leaves linear- lanceolate, entire: style entire. — Adveutized 

 jn waste places near Hickman's Mills, Sheffield and Lee's Summit. 



July-.September. 



4. GALIUM L. 



Herbs with square stems, whorled leaves and small white flowers. 

 Calyx teeth four, or obsolete. Corolla 4- or 3-lobed. Stamens four or 

 three. Styles two. Ovary 2-celled, 2-ovuled. Fruit of two indehiscent 

 carpels. 



