119. RUBIACEAE 223 



1. Whorls of flowers all axillary. 



6. Upper leaves much smaller than the others; moist shaded 

 ground, or in waste places, occasional; introd. from Eur. 



July-Oct. Small-leaved Mint M. cardiaca Gerarde ex Baker 



6. Upper lea\es little, if at all, reduced. 



7. Stem glabrous; moist ground, not common; nat. from Eur. 



Aug.-Oct M. gentilis L. 



7. Stem pubescent or puberulent, at least on the angles; moist 

 ground, common throughout Illinois. July-Sept. [M. 

 arvensis var. canadensis (L.) Briq.; M. arvensis var. 

 glabrata (Benth.) Fern.] Wild Mint M. canadensis L. 



30. CoUinsonia L. — Richweed 



C. canadensis L. Woods, chiefly in southern 111., but extending 

 northward to Clark and Champaign counties. July-Sept. 



31. Perilla L. — Beefsteak-plant 



P. frutescens (L.) Britt. Roadsides, waste places and in woods; 

 natixe of Asia; becoming a common weed in southern 111.; also Peoria 

 Co., V. H. Chase. July-'Oct. 



119. Rubiaceae B.Juss. — Madder Family 



1. Shrubs; leaves opposite or whorled ; flowers in dense globose heads 



2. Cephalanthus 



1. Herbs. 



2. Leaves opposite. 



3. Flowers axillary, sessile or nearly so. 



4. Plants pubescent; fruit separating into 2 or 3 indehiscent carpels 

 4. Diodia 



4. Plants glabrous; fruit a capsule of 2 carpels, one dehiscent, the 



other indehiscent 5. Spermacoce 



3. Flowers pedicellate, cymose or solitary. 



5. Plants trailing: fruit a pair of united red drupes 3. Mitchella 



5. Plants erect; fruit a capsule 1. Houstonia 



2. Leaves apparently in whorls of 4-8 6. Galium 



1 . Houstonia L. — Bluets 



1. Flowers cymose; stems 10-30 cm tall; plants perennial. 



2. Sepals at anthesis longer than the calyx-tube, and in Iruil 

 longer than the capsule; capsule as broad as long. 

 3. Leaves lanceolate; calyx nearly as long as the corolla-tube; 

 the linear sepals much longer than the capsule and about 

 twice the length of the calyx-tube; prairie soil or in open 

 woods in the s. half of the state, extending northw. to 

 Menard and Champaign counties. May-July. [H. pur- 

 purea of auth. not L.] H. lanceolata (Poir. ) Britt. 



3. Leaves linear-oblanceolate to linear; calyx shorter than the 

 corolla-tube. 



