THE VEGETATION OF THE JUAN FERNANDEZ ISLANDS 843 



the terminal bud is unknown, whether as in its supposed nearest relative, 

 Coiiaurodcndrou, or not, but from this it difters by the woolly, long petiolate leaves. 

 l\obinso}iia gavana Dene, "Resino". Compositae. The vernacular name refers 

 to the tjlassy, aromatic resin exsudcd b\' tlie stem and formerly together with 

 the resin from A*, ihurifcya used as a remedy for lieadache. luidemic on Masa- 

 tierra, by far the commonest l\obinso)iia and fortunate!}' the only species found 

 by tiie casual visitor. Frequent in the montane brushwood, descending to about 

 200 m above sea-level and often growing in crevices on the cliff walls, ranging 

 west to the slope of Cerro Chumacera (PI. 66: i; see also Skottsb. 2, PI. 10: i — 2). 

 Rarely as much as 4 m tall, with the main stem several cm thick. Bark gray, 

 I — -2 mm thick, ringed by very dense leaf scars; a thin, fibrous wood cylinder 

 surrounds the soft, whitish pith. Leaves soft, thin leathery as in all species. 

 Branches collected in August, 1908, bore 2 innovations at the base of the old 

 corymb, which dated from 1907 or 1906, as it may take two }'ears or more 

 before a shoot flowers. These innovations had a 2.5 — 3 cm long stem which had 

 shed all its leaves except the apical tuft, ending as in all these species in a 

 characteristic, pointed leaf cone, as illustrated in Skottsb. ?. 59, fig. 12. As a rule 

 2 innovations are formed, one in the a.xil of each of the two uppermost leaves, 

 but sometimes only one is developed. The panicles appear in early summer; in 

 December the innovations were small, sessile and i- — 2 cm long, or they had 

 already begun to lose the lower leaves, so that the apical tuft was borne on a 

 short, naked piece of stem. F'ig. 12 a shows the status at the end of March; I 

 ends in a corymb from 191 5 — 16; II is 2 years old and ends in a fruiting corymb 

 which flowered in December, 19 16, unless II has developed in a single season; 

 most of the leaves have been shed, and all will soon fall. Of the 2 innovations 

 (III) one is favoured. Fig. 12 b was drawn from nature 25.3. 191 7; the earliest 

 leaves, dotted in the figure, were of reduced size and already dead (see also III 

 in 12 a). The genus is dioecious; the corymbs, in spite of being well exposed, 

 are not very conspicuous, the flowers being yellow or dirty yellow in o and greenish 

 yellow in ?. In order to get an idea of the rate of growth a leaf, a, just detached 

 from the closed cone, was marked with a notch on March 25 and the develop- 

 ment of the shoot followed for some weeks: 27.3, b detached, c with point 

 free; 31.3, also c free; 24, (/with the apex free; 8. .4 no perceptible change; 12.4 d 

 half free; 14.4 d free, apex of e free; 20.4 e free, y with top of point free — the 

 rate of growth is slowing down. 



Seeds were sown 26.7. 19 18 and germinated in October, but the j-oung seedlings 

 died during the winter. 



Robi7isonia evenia Phil. Endemic on Masatierra; not uncommon in the upper 

 montane region but very seldom seen below 500 m. Epiphytic on Dicksonia and 

 Bleciinmn cycadifoliiim\ see this volume, no. 7, p. 193. Fig. 13 shows two young 

 plants growing on an old thick Blechnuni trunk. 2 — 3, occasionally as much as 

 4 m tall with a main stem up to 7.5 cm in diameter. Cortex light brownish gray, 

 I — 2 mm thick. Morphology and mode of growth as in R. gayana, but the 

 innovations, commonly 2, may attain a length of 3 — 4 cm already in December; 



