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SCOTT ON THE TREE FERNS OF BRITISH SIKKIM 



17 



vigorous hud is developed on the young and softer parts of the stem. With all this simi- 

 larity of structure, however, there can he no question as to their affinities (as urged by 

 Hofmeister) being other than analogical, and that they are distinct from each other and the 



axillary buds of phaenogams 



by Karsten, and espoused by Mettenias 



Their homology with the latter organ has been suggested 



The latter author has endeavoured to support 



this view from the apparently axiUary partition of the buds in several species of Tricho 



manes, and the transitional condition of those in certain Hymenophylla and Bavalllce, 



which, with axillary buds, have others spinging from the upperside of the superposed 



frond 



These are but isolated instances, however, and 



my opinion are casual rela 



tions, inasmuch as we find in both Trichomanes and DavalUa axillarv buds on certain 



portions of the rhizome, while others a 

 means confined to the line of the fronds 



gularly posed on various parts, and by no 

 Moreover, in many cases, those buds are truly 



nicum and in some of the Indian 



the result of bifurcation of the main axis ; and as such there is no reason why they might 

 not be occasionally subtended by a frond, and so assume an apparently axillary character. 

 This is by no means a rare phenomenon in the erect tufted caudices of Trichomanes j ava^ 



sarmentose species ; in the latter, buds (the results of 

 bifurcation) appear on the frondless end of the stem, and have not unfrequently an 

 axillary relation to a subsequently developed frond. 



In the proliferous tree ferns buds most frequently occur on the exterior base of the 

 stipe, and, though not uncommon (as in Alsophila comosa and glabra, vide Plates X. & 

 XI.) in various extra-axillary positions, I have never observed them in the axil of a frond. 

 The Alsophilce referred to are, remarkably prolific, and, singularly enough, occur in the 

 extremes of altitudinal range of the Sikkim species, viz. A. glabra in low tropical valleys, 

 while the habitats of A. comosa are the temperate forests. In the normal conditions of 



growth of the above species a varying number of adventitious buds are always being 

 produced; 



but for a full exhibition of their wonderful prolificness it is necessary to 



examine plants which, through some 



lopment of the main axis. I was much struck with this in 



other, have received a check in the deve 



glab) 



an uprooted plant of A, 

 This plant I found on the banks of a mountain-steam near the Ganges and 

 Barjeeling road, in the Sikkim Teraie, whence it had no doubt been brought from higher 

 elevations while the stream was flooded, as no other plants of its kind were to be found 

 in the vicinity. Anomalous, therefore, did it appear to observe in a single uniform line 

 of 15 feet, twenty-three young plants of A. glabra, varying from 6 inches to 4 and 

 8 feet in height. Certainly I thought they had been artificially planted, and should have 

 gone onin that belief but for the prostrate and still vegetating stem whence they had their 

 origin, and to which (with many others in less advanced stages) they were yet attached. 

 The production of adventitious buds in A. comosa is similarly copious, and more in the 



natural process of growth 



with a vigorously developing main axis plants are by 



no means rare in which the exterior bases of the stipes in the older parts of the caudex 

 are studded with shoots and buds in various stages of development. By these means the 

 individual plants frequently attain most bulky proportions ; a plant which I measured 

 had an erect caudex 20 feet in height, and presented from 8 feet downwards an elongated 

 cone, with a base 10 feet in circumference, formed by the conjoined adventitious roots 



VOL. XXX. 



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