The Extra-floral Nectaries of Hevea brasiliensis, Miill.- 
Arg. (the Para Rubber Tree), an Example of 
Bud-Scales 1 serving as Nectaries. 
BY 
JOHN PARKIN, M.A., 
Trinity College, Cambridge. 
With Plate XVI. 
W HILE engaged in economic work on india-rubber in Ceylon during 
1898-9, the Para Rubber Tree (Hevea brasiliensis ) 2 was constantly 
under my observation, and peculiar nectaries occupying the position of bud- 
scales on its young shoots attracted my attention. Less conspicuous 
nectaries also occur on the foliage leaves proper. Though these latter 
are incidentally mentioned by systematists, the bud-scales generally, as 
well as their nectariferous nature, appear to have escaped their notice. 
This is not surprising, for the adult tree only puts forth fresh foliage 
annually, and the bud-scales being caducous, are merely evident while 
the shoots are in the immature condition ; thus, unless the tree be ex- 
amined during the short period of leaf-renewal, no bud-scales would 
be seen. 
In the account of the genus Hevea in Martius’ Flora of Brazil 3 , the 
nectaries of the foliage leaves are mentioned, but no reference is made to 
the bud-scales. Delpino 4 in his elaborate work on extra-floral nectaries 
dismisses this genus in a few words, referring apparently only to the 
nectaries of the foliage leaves. 
In a recent paper by Huber 5 on the periodicity in growth of Hevea 
1 The term £ bud-scale ’ is here used in the sense of a reduced leaf-structure situated on the shoot 
below the true foliage leaves. The author does not necessarily wish to imply that such structures in 
Hevea serve or have ever served as protective coverings to the bud. 
2 Introduced into Ceylon in 1876. 
3 Martius, Flora brasiliensis, vol. xi, pars. II, 1873. On p. 298 the genus (nine species including 
H. brasiliensis) is described, as having ‘ petioli communes apice supra glanduligeri.’ 
4 Delpino, Mem. Accad. Bologna, viii, 1887, p. 635. In giving examples of extra-floral 
nectaries in the Euphorbiaceae he refers to Hevea as follows : 1 8 specie di Hevea (petioli ima basi 
patell ari-glanduligeri). ’ 
5 Huber, Bot. Centralb. lxxvi, 1898, pp. 259-64. 
[Annals of Botany, Vol. XVIII. No. LXX. April, 1904.] 
Q % 
