94 DB. HOOKEE AND DR. THOMSON'S PBiECURSORES 



whose characters we have attempted to give. Of all the organs, 

 the rhizome is one of the best-marked ; in most of the species, in 

 all indeed of the Bhodiola section, it is very" large and elongate, 

 sending out few lateral roots, and bearing usually numerous simple 

 annual branches from the axils of membranous bracts towards its 

 apex ; these rhizomes root deep amongst the rocks, and are often 

 divided from the very base into several ascending or erect trunks, 

 each of which, bearing flowering stems, cause the individual 

 plants of some species to attain a great size and rounded or hemi- 

 spherical form. Young specimens of these large-rhizomed species 

 are recognized with great difficulty : they have few prostrate or 

 ascending stems with smaller leaves, and fewer comparatively 

 larger flowers ; and we find, that both in collecting and in sorting 

 our specimens, we have invariably been led to regard the seedling 

 and young specimens as very difierent species from the old. Such 

 seedlings spring up by the banks of rills which have transported 

 the seeds from greater elevations, and as the plants do not under 

 these circumstances attain their proper development, their true 

 origin may long remain unsuspected by the most careful and ob- 

 serving collector. 



The Rhodiola section have, further, almost always robust 

 branches, are perhaps invariably polygamous, and have rather 

 turgid follicles with recurved apices. The leaves are variable in 

 form and toothing, the outer and inner branches from near the 

 apex of the same rhizome having often more or less different fo- 

 liage. The cymes of inflorescence are naked or bracteate ; in some 

 species they are reduced to one or two flowers. The male flowers 

 are often different-looking from the female, having narrower sepals 

 and petals, which do not grow or dilate after flowering, as the sepals 

 of the female plants sometimes do. The sepals are often unequal 

 in size, most so in the male flower. The hypogynous glands do not 

 afford very good characters, being variable in length and breadth, 

 and in some species they are almost absent. 



The remaining species are generally hermaphrodite, but not 

 always so ; they have usually more slender follicles with subulate 

 or filiform erect styles. 



The most alpine species are liable to excessive variation in 

 stature, and size and colour of flower, from white to deep rose or 

 red purple, and from orange to golden yellow. In most species 

 the stamina are longer than the petals, and they generally pre- 

 serve their proportionate length to a considerable degree ; but 

 frost-bitten specimens are often deceptive, and have sometimes 



