68 THE VOYAGE OF H.M.S. CHALLENGER. 



TJMBELLIFBR^S. 



Sium burchellii, Hemsl. (Plate XLVIII. C, figs. 5-7). 

 Sium burchellii, Hemsl. 



Lichtensteinia burchellii, Hook. f. in Hook. Ic. PL, xi. t. 1033 (incorrect as to the fruit); Melliss, 

 St He!., p. 278, t. 33. 



St Helena. — Endemic. Diana's Peak — Burchell, 92 ; near Taylor's Flat to the west- 

 waul of Diana's Peak — Melliss. 



" Dwarf Angelica." 



After a careful comparison of all the materials accessible, we have no doubt that this was 



erroneously referred to the genus Lichtensteinia, aud we strongly suspect that it is not 



specifically different from Sium helenianum, but merely a stunted condition of that plant ; 



yet, as we have only young fruit of Sium burchellii, we cannot be sure. There seems to 



have been some confusion of the two forms and perhaps a third. The obvious divergences 



of the two forms, whatever their rank, are in stature and in the length and shape of the fruit. 



Sium burchellii grows only three to five feet high, and has a longer, narrower fruit, with 



prominent, corky juga ; while Sium helenianum grows from eight to twelve feet high, and 



has a shorter, thicker fruit, with less corky and more angular juga. These differences may 



be due to habitat, for Sium helenianum is said to stow amonest the "Cabbage-trees" and 



ferns in the ravines that traverse the mountain sides of Diana's Peak; whereas Sium 



burchellii, according to Melliss, inhabits the southern precipitous sides of the high central 



ridge, and is now very rare. The fruit of Sium burchellii, taken from the type specimens, 



has no vittse under or in the juga ; aud the number of vittse in the valleys is usually two, 



but varies from one to three in different fruits, or different valleys of the same fruit ; when 



there is only one it is relatively large. In Sium helenianum the number of vittas in each 



valley seems to be constantly three. Other reasons why we think they are forms of one 



species are — our inability to sort the specimens into two species, aud the fact that neither 



lloxburgh nor Burchell, both of whom were good botanists (and the latter spent five years 



in the island), recognised more than one species. Further, Melliss sent specimens to Kew, 



collected by Mr Chalmers l near Diana's Peak, with the note, " appears to be different from 



Sunn helenianum and Lichtensteinia burchellii." This intermediate form strengthens the 



view that the original types of the two forms are merely states of the same species. Loose 



fruits sent by Mr IVIelliss as Lichtensteinia burchellii are exactly the same as loose fruits 



sent by him under the name of Sium helenianum, and both the same as typical fruit of the 



latter ; so he, we may infer, was unable to distinguish the supposed species on the spot. On 



the other hand, Mr D. Morris, who visited the island in 1883, was of opinion that there 



were two distinct species, though we may add he collected only one. Melliss"s 46 has the 



following note : " This is the plant that Burchell gathered. It grows on the Central Ridge, 



1 Mr .John Chalmers was sent out in 18G8 to establish the Cinchona plantations, which have been since 

 abaiiduned. 



