1<)4 Allgemeines 



early part of the next dry season, and shedding the seeds upon 

 the rocks." 



In the genus Tristicha, whieh is represented by the Single species 

 T. ramosissima (Wight), Willis in India, the primary axis is still un- 

 known. The thallus (i. e. the horizontal portion of the mature plant, 

 which is in rnore or less intimate contact with-, the rock, cfr. p. 410), is 

 a creeping Filament with a well-marked root-cap at its apex: it is fre- 

 quently endogenously branched, the branches being usually at right 

 angles to the main thallus. The thalli are attached to the rock by root- 

 halrs and by „feet" of varied shape — often thin disc-like structures — 

 arising in pairs from the sides of the thallus. At these points also the 

 endogenous secondary shoots appear, haptera being developed below 

 them from the disc-shaped expansions just mentioned. In this genus 

 the secondary shoots attain considerable size, and float out freely in the 

 water; at a very early stage they themselves develop shoots of the se- 

 cond order, which are of limited growth (ramuli). Both kinds of shoots 

 are provided with large numbers of delicate, moss-like leaves, those on 

 the ramuli being rather smaller than those on the main shoots ; the leaves 

 do the chief assimilating work of the plant Between the ramuli, which 

 in the mature state appear to be situated a little to oue side of a leaf on 

 the main shoot, and the main secondary shoot itself further shoots of 

 unlimited growth are formed ; but many of these remain dormant until 

 the flowering period, when they give rise to short floral axes, bearing a 

 terminal flower, only two or three ramuli being formed on these shoots. 

 The uppermost, slightly enlarged leaves of the floral axis are converted 

 into a shallow cup round the base of the flower's pedicel. Occasionally 

 such short floral shoots, generally unbranched and bearing one or two 

 ramuli, arise directly from the thallus." After flowering the pedicel leng- 

 thens and at the same time the small-celled tissue surrounding the vas- 

 cular tissue becomes thick-walled and lignified", and finally the outer 

 cortex falls away altogether, leaving the ripe fruit standing on a long 

 thin filamentous stalk, which is highly elastic. This curious feature is 

 also observed in all the following genera. The anemophilous flower has 

 a membranous perianth, three stamens, and a superior trilocular ovary 

 with three long hairy stigmas. The fruit resembles that of Lauria. 



In Lauria zeylanica Tul., which is confined to Ceylon and 

 Western India, the exalbuminous seed, whose testa is mucilaginous 

 in all the genera under discussion (a feature, which may possibly aid 

 distribution by causing adhesion to the feet of wading birds), bursts open 

 when wetted and the hypocotyl immediately bends down to the rock, 

 becoming attached to it by numerous rhizoids. Its base expands and 

 ultimately forms a kind of tuber, on which the two cotyledons and a 

 few subsequently-developed leaves are borne. Soon, however, the growth 

 of the seedling begins to take place in a lateral direction at right angles 

 to the plane of the cotyledons, so that the seedling becomes dorsiven- 

 tral ; there is no further development of leaves in the vertical direction, 

 the newly-formed ones all leaning towards the growing apex, which is 

 provided with a kind of collenchymatous cap on its under side. In later 

 stages, when the thallus begins to branch, a very marked dimorphism 

 in the leaves is to be observed; those on the thin edges of the now 

 more or less flattened thallus are large and ovate, whilst on the upper 

 surface of the growing tip a dense irregulär crowd of linear leaves is 

 formed. The apparent dichotomy of the thallus is probably really a case 

 of lateral branching, the branch arising very close to the apex. The 

 formation of new apices is very rapid, giving the apical parts of the 

 thallus a fan-like appearance. Assimilation is probably carried on in 

 both leaves and thallus. Numerous secondary shoots are formed in the 

 angles between the branches of the thalli and also very commonly from 

 its thin marginal portions; their growing apex however does not emerge 

 from the thallus, only the leaves bursting out and forming a symmetrica! 

 rosette. The flowers arise directly from a single growing point of the 

 thallus, at its apex or margin, and are not developed on a secondary 



