CIV.— THE REFLEXED-LEAVED STONE-CROP. 
Sedum reflexum Linne. 
O NE of the most important and most interesting starting-points in the evolution 
of Dicotyledons is presented by the great Order Rosales. Its varied but often 
ill-defined Families comprise alike plants with flowers of a very primitive type and 
others very highly specialised in structure and function. In most cases their floral 
organs are cyclic or whorled ; and, though sometimes apetalous, they are generally 
heterochlamydeous ; so that they represent a higher grade of evolution than the 
RanaleSy with which, however, they have much in common. A flower such as that 
of the Bramble or of Herb Bennet, with five sepals, five petals, and indefinite stamens 
and carpels, the latter not united and each of them one-seeded, seems at first sight to 
differ but little from that of a Buttercup. As in Ranunculace^e^ the higher types are 
monosymmetric, though polysymmetry prevails in most Families of the Order. 
As too in the lower group, the carpels vary in number from one to an indefinite 
number, and may be either free or united. The main distinction would, in fact, 
appear to be in the “ insertion ” of the petals and stamens. Whilst in Ranales this 
is generally— though not always — hypogynous, the primitive condition which we saw 
so well illustrated in the Mousetail (Myosurus') in Plate LXXXII, in Rosales it is 
generally — though not always — perigynous. The floral receptacle, that is, instead 
of tapering from the base of the flower upward, is arrested in its elongation and 
grows out, at some distance behind its apex, laterally into a disk, or first laterally and 
then upward into a cup or so-called “ calyx-tube.” In some cases this not only 
surrounds but adheres to and imbeds the carpels, so that the ovary becomes 
“ half-inferior ” or “ inferior,” and the petals and stamens, appearing to spring from 
the top of it, may become epigynous. 
Of thirteen Families included in the Order, four, and those the four largest, are 
represented in our British Flora ; and their importance may be gauged from the fact 
that here we devote no less than forty-three Plates — the remainder of this volume — 
to them. These four Families are the Crassulace^e^ Saxifragacete^ Rosace<£, and 
Leguminos^. 
The Crassulacea form a considerable and very natural Family of herbs and 
shrubs, numbering nearly five hundred species in fifteen genera, of which Sedum 
comprises 140 species, Crassula 100, and Cotyledon 90. The group is cosmopolitan, 
but it is represented in especial abundance and variety of forms in South Africa. 
Most of them grow in the very driest situations, naked rocks, old walls, or hot sandy 
plains, where not a blade of grass can live ; and most of them are perennials specially 
adapted for these conditions by their xerophytic structure. Their stems, and still 
more generally their leaves, are succulent, being thick and containing a considerable 
reserve store of water — often mainly derived from dew — which is retained by their 
thick and often glaucous cuticle with a few sunken stomata. The leaves are also 
