442 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [Vol. 8, No. 5 



Epilobium neriophyllum Hausskn. Abh. Naturw. Ver. Bremen 7: 19. 1880; Monogr. Gatt. 



Epilobium 2361 1884. 



Zomba District: Zomba Plateau, frequent on wet open banks of a rain-forest 

 stream, up to 1.5 m. high, flowers white, later pink, 1500 m., June 7, 1946, 16314. 

 Abyssinia, southward to South Africa, westward to the British and French Camer- 

 oons and Angola; also in Madagascar. 



Jussiaea erecta L. Sp. PI. 388. 1753; Munz, Darwiniana 4: 195. 1942. 



Jussiaea linifolia sensu Oliv. Fl. Trop. Afr. 2: 489. 1871; Hutch. & Dalz. Fl. W. Trop. 

 Afr. 1: 146. 1947. excl. spec. Brown-Lester 10; non Jussiaea linifolia Vahl. 



Kota-kota District: Benga, west shore of Lake Nyasa, scattered on sandy 

 beaches, herb 50-60 cm. high, stem erect, stem and leaves reddish, flowers yel- 

 low, 470 m., Sept. 2, 1946, 17486. Chikwawa District: Lower Mwanza River, one 

 plant on a sandy beach, herb 1 m. high, flowers small, yellow, 180 m., Oct. 4, 

 1946, i7957. Tropics of the Old and New Worlds. 



Jussiaea suffruticosa L. Sp. PI. 388 (1753) var. brevisepala Brenan, Kew Bull. 

 1953: 168. 1953. 



Kota-kota District: Benga, west shore of Lake Nyasa, occasional on sandy 

 beaches, herb, branches prostrate and spreading radially, flowers yellow, 470 m., 

 Sept. 2 » 1946, 17485. Chikwawa District: Lower Mwanza River, uncommon on 

 sandy river-beaches, 60-70 cm. high, flowers yellow, 180 m., Oct. 6, 1946, 18014. 

 The species pantropical; the variety widespread in tropical Africa. 



Jussiaea abyssinica" (A. Rich.) Dandy & Brenan in F. W. Andrews, Flow. PI. 

 Anglo-Egypt^Sudan 1: 145* 1950. 

 Ludwigia abyssinica A. Rich. Tent. Fl. Abyss. 1: 274. 1848. 



Ludwigia prostrata sensu Oliv. Fl. Trop. Afr. 2: 491. 1871; Perrier, Not. Syst. 13: 

 140, 141. 1947; Robyns, Fl. Spermat. Pare Nat. Albert 1: 681. 1948; nec non auct. 

 afr. al.; non Ludwigia prostrata Roxb. 



Isnardia prostrata sensu Hiern, Cat. Afr. PI. Welw. 1: 381. 1898; non Isnardia prostrata 

 (Roxb.) Kuntze. 



Jussiaea acuminata sensu Hutch. & Dalz. Fl. W. Trop. Afr. 1: 146. 1927, pro maj. 

 parte, excl. spec. Vogel 72, Millen 149] non Jussiaea acuminata Sw. 



Mlanje District: Likubula Gorge, herb about 1 m. high, freely branched, leaves 

 more or less fleshy, flowers yellow, about 3 mm. in diameter, 840 m., June 20, 

 1946, 16381. Widespread in the African tropics, extending to Natal and 

 Madagascar. 



Hitherto most workers on African botany have been content to follow Oliver's 

 lead in identifying this plant with the Asiatic Ludwigia prostrata Roxb. That, 

 however, while very similar in general appearance, differs profoundly in having 

 the seeds free within the capsule and not encased in little pieces of endocarp 

 like tharse of Jussiaea abyssinica. In addition, the capsules of L, prostrata are 

 much more angled and sulcate longitudinally than those of /. abyssinica, and 

 under a x 20 lens a very minute puberulence is visible on the young ovaries of 

 L prostrata, and absent from those of the other species. So far L. prostrata ap- 

 pears to be absent from Africa, and /. abyssinica from Asia. 



Examination of herbarium specimens and floras shows that botanists have 

 found it very difficult to separate /. abyssinica from African material of /. lini- 

 folia Vahl (/. acuminata auct.), probably because both plants have the seeds en- 

 cased in little pieces of endocarp. Besides the difference in stamen number 

 (4-5 in /. abyssinica, 8 in linifolia), there are certain characters that enable 

 these two plants to be safely separated without dissection. In /. abyssinica the 

 flowers are more or less fascicled in the leaf-axils, while in /. linifolia they are 



18 By J. E. Dandy [British Museum (Natural History)] and J. P. M. Brenan. 



