TREE EERNS OE NORTii AMERICA — MAXON. 47l 



the West Indian. Cyathea elegans and Alsophila aquilina and the Costa 

 Rican A. crassifolia) , which exhibit this character to a marked degree 

 in their young state, in age develop clean trunks, with definite even- 

 surfaced scars. 1 The appearance of a trunk sheathed with broken or 

 hanging fronds is much less attractive than that of stems from winch 

 the leaves are freely deciduous; yet a few, like Cyathea Brunei, more 

 than make up in sheer massiveness whatever they may lack in ele- 

 gance and graceful proportion. 



The arrangement of the leaves upon the stem may be observed 

 best in species which have smoothish trunks, as in the common 

 form of Cyathea arhorea, shown in plate 3, figure A. In these the 

 leaf scars may be either widely spaced or rather compactly set 

 together, forming a rough but regular mosaic pattern; if the latter, 

 the trunk is said to be tesselate. In most there may be noted a 

 definite spiral arrangement, which differs according to the species 

 and, exceptionally, among individuals of the species. In Cyathea 

 aureonitens, however, and probably in others, the scars are not 

 spirally arranged nor closely set, but uniformly appear in distinct 

 horizontal zones, the six to eight leaf scars of each forming a separate 

 distinct girdle about the trunk, 8 to 12 inches from the one above or 

 below. 



RESTING PERIODS. 



Cyathea aureonitens has also another unusual feature, that of 

 shedding all its fronds, after maturity, at one time, seasonally, 

 a trait which it shares with several other species of the same genus, 

 Cyathea concinna and C. Tussacii of Jamaica and C. insignis of 

 Jamaica and Cuba. Concerning the first of these Jenman remarks 

 that "like C. Tussacii, in the resting season, in late spring or toward 

 midsummer, it drops all its fronds, the large stout trunk, a uniform 

 diameter from top to bottom, standing, postlike, till growth begins 

 again." With respect to C. Tussacii he writes, "In some instances, 

 late in the resting season, about May or June, the fronds all drop 

 away, leaving the bare trunk. When vegetation begins again a 

 whorl is thrown up together." Cyathea insignis, also, "like the 

 two preceding, makes its growth periodically, throwing out a tier of 

 fronds at once and then resting for an interval." In Cyathea 

 aureonitens, as I have observed it in western Panama and Costa 

 Rica, not only the large tripinnatifid fronds themselves but also 

 their component leafy parts, the pinnse and pinnules, are sometimes 

 freely deciduous; the latter were even observed to fall first, leaving 

 the leaf stalks and nearly bare midribs of the huge leaves standing 

 out temporarily like stout whip stalks before they also should fall. 



i A similar tendency toward bushy growth from long-persistent leaves is noted in young plants of certain 

 palms, as, for example, the common "coroho" of Jamaica (Acricomiafusiformis). 



