1G8 THE JOURNAL OF BOTANY 



THE GENUS CTENOMERIA. 

 By Sir David Prain, F.R.S. 



The South African Euphorbiaceous genus Ctenomeria was 

 established by Harvey in 1842 (Hook. Lond. Journ. Bot. i. 29) for 

 C. cordata Harv., a Natal plant collected by Krauss. This species, 

 which has otherwise all the facies of a Tragia, has 50-60 stamens 

 in place of the usual 3 ; its generic status was deduced by Harvey 

 from this fact. In 1845 Hochstetter (Flora xxviii. 85) based upon 

 " Krauss 186 " his species C. Kraussiana. Failing to find in its 

 male flowers more than 40 stamens Hochstetter was satisfied that 

 this plant must be specifically distinct from that on which C. 

 cordata Harv. was founded. In another plant, also a Ctenomeria, 

 collected in the Uitenhage division by Drege, and issued as Drege 

 8239, Hochstetter did find 60 stamens ; this plant he therefore 

 concluded must be the one intended as C. cordata by Harvey. 

 But the examples of C. cordata Harv. in herb. Kew and herb. 

 Dublin also bear the number " 186," so that the type of C. cordata 

 is a co-type of C. Kraussiana, and these two names denote one 

 species. We now know that the range of variation in the number 

 of stamens is from 30 to 60. The large number of stamens in the 

 male flower is not the only effective character in differentiating 

 Ctenomeria from Tragia ; quite as important is the circumstance 

 that in Ctenomeria the styles are long, slender, flexuous, free, and 

 fimbriately stigmatic throughout their length. 



The genus was accepted by Endlicher in 1843 (Gen. PI. Suppl. 

 III. 98) ; by Sonder in 1850 (Linnaea xxiii. 110) ; by Baillon in 

 1858 (Mud. gen. Euphorb. 494), and in 1862 (Adansonia iii. 161). 

 But in 1866 Miiller (DC. Prodr. xv. 2, 925), while keeping 

 Ctenomeria apart from Tragia, associated with it, owing to both 

 having numerous stamens, the genus Leptorhachis Kl. based by 

 Klotzsch in 1841 (Wiegm. Archiv. vii. 189) on a Brazilian species 

 which differs markedly from Ctenomeria as regards the nature of 

 its anthers and of its styles. In 1868 Hooker (Harv. Gen. S. Afr. 

 PI. ed. 2, 339) did not admit that Ctenomeria is congeneric with 

 Leptorhachis. Shortly thereafter Miiller reconsidered his conclu- 

 sion, and in 1874 (Mart. Fl. Bras. xi. 2, 403) reduced Leptorhachis 

 to Tragia, a proceeding which only concerns us because Miiller at 

 the same time reduced Ctenomeria to Tragia. In 1880 Bentham, 

 (Gen. PL iii. 329) after showing how little ground there is for 

 uniting Leptorhachis and Ctenomeria, again reduced both to 

 Tragia. In this Bentham was followed by Pax in 1890 (Nat. 

 Pflanzenf. iii. 5, 65) with, however, the improvement of treating 

 both Leptorhachis and Ctenomeria as distinct sections. Pax 

 might, as regards the latter, have treated it as the valid genus 

 it is. Instead, he reverted in 1898, perhaps unintentionally, to 

 Miiller's position of 1874 by publishing as Tragia Schlechteri 

 Pax (Bull. Herb. Boiss. vi. 735) a Natal plant which is certainly 

 a Ctenomeria, and is perhaps too closely related to C. cordata 

 Harv. 



