XVI. SELA.GH1VEL.L.A-OEAJE. 



Terrestrial, exceptionally epiphytical. Shoots elongated, creeping, 

 ascending or erect, sometimes scandent, branched, often proliferous at 

 the base or springing from a creeping or scandent main stem, or the 

 branches growing out to new shoots, with the root fibres confined to the 

 base or to the nodes of the lower half or extending to the higher nodes; 

 steles 1 — 5, rarely more, if solitary then central, if double then one 

 ventral and the other dorsal, if triple then a central one placed between 

 the dorsal and ventral, if 4 — 5 then the ventral or (and) dorsal one 

 double, if more than 5 then often irregularly arranged but nearly always 

 placed in parallel hnes. Leaves (') simple, mostly very small, isomorphous 

 or heteromorphous, occupying both stem and branches, rarely multi- 

 farious (i. e. isomorphous and placed in more or less compound whorls 

 or spirals), sometimes tetrastichous (i. e. isomorphous and placed in 4 

 rectangularly decussate rows, so as to form perfectly square stems and 

 branches), more commonly platystichous (i. e. heteromorphous and 

 arranged in 2 parallel planes, those of the lower plane [lateral leaves] 

 larger, more or less spreading to erecto-patent and placed in 2 opposite 

 rows, those of the upper plane [intermedial leaves] erect or suberect and 

 placed in 2 contiguous rows, so as to form rather flattened dbrsiventral 

 stems and branches), those of the stem often distant, of the branches 

 generally more contiguous, at least the younger leaves provided with a very 

 minute decoloured appendix or ligula (*) on the upper (inner) side at the 

 base, the margin and the aligular surface not rarely provided with groups 

 or longitudinal rows of sclerotic cells, so as to form sharply bounded, 

 pale, decoloured or pellucid edges and (or) intramarginal to subcostal 

 spurious veinlets ('). Spikes terminal on the branchlets or rarely placed 



(') The description of the leaves must be understood (unless it is otherwise 



stated) to refer to those of the branchlets excluding the sporophylla, not to those 



of the stem, which, especially in the species with heteromorphous leaves, often 

 differ widely from those of the branchlets in shape, size and direction. 



(^) Visible by high magnifying power only. 



(') Often a valuable specific character. The pale, pellucid or decoloured edge 



should not be confounded with the hyaline acroscopic base of the lateral leaves, 



