62 AERIDE>:. 



plants so firmly as to enable them to resist any of the ordinary force 



of Nature that would affect their stability or cause their displacement. 



As the stems continue to lengthen, adventitious roots are constantly 



produced from the preceding year's growth, which attain a great length, 



frequently branch, and become pendent by their own weight. These 



roots thence form in time a tangled, cord-like mass that cannot be 



aptly compared Avith any phase of vegetation seen in our climate. 



The annual lengthening of the stem is well marked by the foliage, 



Avhich in a wild state is of biennial duration : the roots too that are 



farthest removed from the foliage gradually cease to perform their 



functions and die ofi'. The inflorescence is produced from the axils of 



the leaves of the preceding year, which begin to wither in the short, 



dry season that ensues after the gro\vth of the current year is 



completed. As the stem of an Aerides lengthens by successive yearly 



growths it gradually deviates from its ascending position, first becoming 



more inclined, then taking a horizontal direction, and finally by its 



own weight and the weight of its appendages it is brought into almost 



an inverted or, if near enough to the ground, a prostrate position, 



when its further lengthening is cliecked or even arrested by the 



obstacles it encounters. Nevertheless, the stems of Aerides are virtually 



interminate, they would continue to lengthen indefinitely if no physical 



obstacles or checks intervened. Stems have been observed from 15— -20 



feet long, but long before that length has been attained young shoots 



spring from the base of the parent stem, Avhich in time become 



independent plants ; the stem also produces later^d shoots when a 



fracture has occurred, or when growth at the apex has been arrested 



by some physical cause. As the leaves wither the stem becomes 



lio-nified, sapless, and gradually loses ' all signs of life beyond a certain 



distance below the foliage ; probably the life of no part of the stem 



under the most favourable circumstances exceeds five years. 



Such is the general view of the most obvious period of the life 



history of an Aerides in its native home.* Many exceptional cases 



are doubtless to be met with, but in none that have come to our 



knowledge has the general law been greatly departed from.t Under 



the artificial conditions to which the Aerides are subjected in the 



glass houses of Europe, some modifications of the general law of 



their growth as sketched above are occasionally observable, especially 



in the longer persistence of the foliage and prolonged life of the stem. 



* The above general view of the life history of an Aerides is also applicable to Vanda, 

 Saccolabiuni, etc., and other allied genera, with but some modification, and therefore will not 

 be repeated under them. 



t Aerides ja'ponicum is a diminutive species, whose stem probably never exceeds a few inches 

 in height under the most favourable circumstances ; its life history is, however, essentially the 

 same as that of other Aerides. 



