322 Transactions. 



(c.) Rubus cissoides. 



A. LIFE-FORM. 



This species occurs in the forest in most situations, and though not 

 crowing to a great size, nevertheless exhibits greatly varying habits of 

 growth. On the smaller trees and on the shrubs its growth resembles that 

 of other species of Rubus, but, like R. suhpauperatiis, it abounds on the 

 outskirts of the forest, where it forms straggling masses with leaves reduced 

 to midribs.* In numerous cases certain shoots scramble into a tree, in 

 whose shade the leaf-blades are well developed. Other branches of the 

 same plant stretch along the ground and form the wiry masses charac- 

 teristic of the plant in these situations, while branches between these 

 two portions bear leaves which exhibit all gradations in leaf-reduction 

 (Plate XXIII). The prickles, unlike those in R. suhpaiiperatus, are absent 

 from the stem, and are practically absent on the leaf-lamina, although as 

 many as three may sometimes be present. The stems are covered with a 

 greyish-brown bark, and grow to a thickness of 5 cm. in diameter. Leaves 



/ 

 Figs. 3, 4. — Rubus cissoides. Climbing-leaf. 



with smaller laminae possess more prickles, while in the final stages of re- 

 duction the midrib may bear as many as 25. The prickles form a feature 

 by which this species can be readily distinguished from R. subpauperatus, 

 for in R. cissoides they are yellowish, but in the latter red. 



Especially characteristic of R. cissoides is the production of adventitious 

 shoots. These are green, thus being fitted for photosynthesis, and the 

 internodes are relatively long- — e.g., 15 cm. or more ^ — and in some cases 

 1'7 cm. in diameter, and stand erect for 2-5-3 m. The leaves of such shoots 

 are almost reduced to greatly elongated midribs. A typical shade leaf has 

 a terminal leaflet 5-7 cm. in length, and rather shorter lateral leaflets ; but 

 the leaves of adventitious shoots may have their terminal midrib 21 cm. 

 long and their lateral midribs 13 cm. As these leaves project from the 

 stem at right angles, and bear large numbers of prickles, it can be seen how 

 important they are in aiding the plant to reach new supports. 



Very often the liane is found straggling along the forest-floor for nearly 

 10 m. In places where the undergrowth is scanty Rnhns cissoides forms 



* This is the so-called var. 2^<^'><'peratus (J. B. Arirst.) T. Kirk. 



