Family 3. PENTHORACEAE 



By Per Axel Rydberg 



Perennial herbs, with rootstocks and alternate leaves. Flowers perfect, 

 in terminal cymes, secund on the spreading branches. Hypanthium scarcely 

 developed. Sepals 5 or 6, greenish, distinct. Petals as many as the sepals, 

 inconspicuous, greenish, or wanting. Stamens twice as many as the sepals, 

 hypogynous ; filaments filiform ; anthers oblong, dehiscent by longitudinal 

 slits. Gynoecium of 5 or 6 carpels united to the middle ; styles short, and 

 abruptly pointed ; stigmas capitate. Ovules numerous in each carpel, on axial 

 placentae. Fruit depressed, composed of 5 or 6 follicles, inserted obliquely 

 on the pyramidal receptacle and united about half their length, each follicle 

 circumscissile just above their union. 



The family consists of only the following genus : 



1. PENTHORUM (Gronov.) I.. Sp. PI. 432. 1753. 



Characters of the family. The genus contains two species, natives of China and the 

 Amur District, and the foUowing. 



Type species, Penthorum sedoides L. 



1. Penthorum sedoides ly. Sp. PI. 432. 1753. 



Penthorum circinale SaUsb. Prodr'. 308. 1796. 



A bright-green weed-like plant, glabrous, or glandular-pubescent above. Stem 1-6 

 dm. high, simple and terete below, branched and angled above ; leaves shining ; petioles 

 0.5-2 cm. long; blades elliptic-lanceolate or elliptic, 3-15 cm. long, acuminate at both ends, 

 finely serrate; cymes 2-3-branched, their branches 2-8 cm. long, spreading; flowers light- 

 green; sepals triangular-ovate, 1.5 mm. long, acute; petals linear or linear-spatulate, 

 usually wanting ; fruit 4-5 mm. broad, each follicle tipped with a spreading beak. 



Type locality : Virginia. 



Distribution : New Brunswick to Florida, Texas and Minnesota. 



Illustrations : Hill, Veg. Syst. 13 : pi. 6; Gaertn. Fruct. pi. 65 ; Lam. lU. pi. 390 ; Baill. 

 Hist. PI. 3 : /. 376, 377 ; K. & P- Nat. Pfl. 3'^* ; /. 22 ; Britt. & Brown, 111. Fl. /. 1821. 



VOI.UME 22, Part 1, 1905] ' 75 



