341 



P 



[L 



1 



Leaves all alternate 6. D. sativa. 



Leaves some alternate, some 7. D. xillosa. 



opposite 



Leaves ovate, all opposite 



/ 



The main defect in this system, it will be seen, lie* 

 in the ^ distinction relied upon in discriminating- between 

 D. sativa as delimited in 1737 and D. rillnsa, newly 

 intercalated in the system in 1753, since specimens of the 

 latter collected from such portions of the plant as may be un- 

 provided with opposite leaves must of necessity be attributed to 

 the former. Another defect, which in the existing state of 

 botanical knowledge it was impossible to appreciate in 1753, 

 results from the fact that species beset with prickles may produce 

 shoots that, especially towards their extremities, are unarmed, 

 and that species which produce bulbils in the same way may de- 

 velop shoots, the leaves on which are not bulhilliferous, so that 

 particular specimens derived from a plant that according to the 



f above kev are really referable to D. aculeata or to I), bulbifera 



may, in the absence of a knowledge of the whole individual to 

 which they belonged, be placed of necessity under D. sativa. AVe 



; shall find indications as we proceed that Linnaeus himself, and 



others who have relied, perhaps too implicitly, on his authority, 

 have been led to interpret too widely the specific limits of 



J D. sativa. On the other hand we shall find that those who have 



been led to realise the difficulty now explained have not alwavs 

 been in accord as to which of the incongruous elements that accord 

 with the Linnean definition should enjoy the distinction of 

 bearing the designation T). sativa. 



| It is not necessary for the purpose of our enquiry to deal ex- 



haustivelv here with the various references and citations under 



the other seven segregates proposed by Linnaeus in 1753. It is, 



however, desirable to understand exactly what the plants are 

 which he treated as belonging to D. sativa. In 1737 (Sort. Cliff. 

 p. 459) Linnaeus cited as the male of his species Ricophora 

 indica s. Inhame malabarica, folio rotundo in aeuminatissimnm 

 opicem mucronato (Plul\ Aim. p. 321) and Mukelengu (Rheed. 

 Ilort. Malab. vol viii. p. 9T. t. 51). A reference to Plukenet 

 shows that the descriptive phrase quoted was taken up by 

 Plukenet from Hermann (Par. Bat. Prodr. p. 371) and a reference 

 to Hermann shows that the phrase was coined bv him to indicate 

 the Mtt-kelengu of Kheede. These two references to the male of 

 D. satira therefore both relate to the same Old World plant. 

 Under the female of the same species Linnaeus cited three plants, 

 all from the "Western Hemisphere; 1. Dioscorea scandens, foliis 

 tamni, fructu racemoso (Plum. Gen. p. 9); 2. Volubilis nigra, 

 folio oordato nervosa (Sloan. Cat. Jam. p. 46 and Hist. Jam. 

 vol. i. p. 1401 : 3. but in this case doubtfully, Rhizophora 

 americana [Boerh. Ind. alt. Jjugd*-Bat. vol. ii. o. 267). The 

 plants of Plunder and Sloane were West Indian species, one 

 known to us from Plumier'< figures (Plum. Gen. t. 26 and Bunn. 

 PI. Amer. Plum. t. 117. fig. 1), the other from Sloane's original 

 specimen still preserved in the herbarium at the British Museum; 



