I 



MOEPHOLOGY. 



them (P. Wallichii). And in the species with thickened underground rhizomes that emit 

 fla"ella which give out fibrous rootlets and are prolonged upwards into apparently 



annual stems (P. trichoglossa, Clarkei, Prainiana) the radical leaves are evanescent. The 

 cauline leaves may be few in number, and then may resemble the radical leaves 

 (P. Wallichii) , or be markedly unlike them (P. lachnoglossa). But usually the cauline 

 leaves are somewhat numerous, differing from the radical leaves mainly in being more 

 shortly petioled or altogether sessile and in having smaller laminae. The transition as a 

 o-eneral rule is <radual where the species has alternate leaves, more abrupt if the leaves 



be verticil late. But the transition may be abrupt where the leaves are alternate (P. lack- 

 noglossa), or gradual where they are whorled (P. rex). The length of the petiole is very 

 variable, sometimes it is slightly winged (P. alaschanica\ very rarely much expanded so 

 that adjacent petioles become connate in a membranous ochreate sheath (P. rex). Very 

 often all the cauline leaves are sessile; the radical leaves may also be sessile (P. Clarkei), 

 but this is extremely rare. In alternate-leaved species the lamina is usually lanceolate, 

 loss often ovate (P. Collettii), while in species with opposite or whorled leaves the lamina 

 is oftener ovate than lanceolate (P. Heydei). Though the margin is sometimes no more 

 than crenate (P. bella, carnosa), it is never in Indian species quite entire •} more generally 

 the lamina is pinnatifid to partite ; often it is twice pinnate, sometimes even thrice divided 

 (P. ezcelsa, Kingii). The extent of division diminishes as the lamina itself decreases in 

 size towards the apex of the stem. 



The floral leaves may be only distinguishable, if distinguishable at all, from the 

 cauline in size, in which case the flowers are merely axillary (P. fragilis, Jlexuosa 7 gibbera). 

 This is most usual in species with verticillate leaves. These floral leaves are then 

 generally smaller than the cauline ; sometimes, however (P. flexuosa), they are of the 

 same size, rarely (P. denudata) the lower floral leaves are distinctly larger. But at times 

 in verticillate-leaved species, and usually in those with alternate leaves, the floral leaves 

 are modified into distinct bracts. In a few cases the transition to the bract region is 

 sudden (P. excelsa); as a rule it is gradual, and the lowest flowers occur in the axils of 



what are only smaller cauline leaves. Bracts vary from ovate to lanceolate, with 

 margins serrate throughout (P. lachnoglossa), serrate only at the apex (P. trichoglossa), 

 or entire (P. tenuirostris) ; are usually sessile and represent only a modified lamina, 

 but are sometimes distinctly petioled (P. exeelsa), and occasionally represent mainly a 

 modified petiole with only the rudiment of a lamina left at the tip (P. Oederi\ 



The flowers may be sessile or sub-sessile and the inflorescence sub-capitate or sub- 

 spicate, or distinctly pedicelled and the inflorescence racemose. When this is accompanied 

 by a loosely branching stem (P. gracilis, Kingii) the inflorescence becomes paniculate. 



When pedicels are present the flowers are usually erect ; sometimes (P. curvipes, resupinata) 

 they are deflexed. 



The flowers as a rule open centripetally, but it is by no means unusual for those in 

 the lower axils to open later than the rest, as exceptions (P. dolichorrhiza , villosa), or as 



a rule (Sipfionanth.k generally). In the former ease it is clearly not an instance of 



centrifugal opening; in the latter it is by no means certain. The condition is constant 

 among the Siphonantm, and the evidence from herbarium material will be examined in 

 connection with the subject of aestivation, but careful field observation is necessary in 

 order to clear up the point. There are, however, frequent examples in high Alpine 



1 The leaves in two species-both American (P. angustifolia, Howellii)-wi undivided. 



