CXXXIV. — THE PETTY WHIN. 
Genista anglica Linne, 
I N spite of their undoubtedly close relationship, the contrasts between the Rosacecs 
and the Leguminosce are most remarkable. The latter, which is often known as 
the Pea and Bean Family, is the second largest Family among Flowering Plants, 
numbering some eleven thousand species in some four hundred and fifty genera. 
It comprises many larger trees than occur among the Rosacece, is, perhaps, more truly 
cosmopolitan, and is certainly far better represented in the Tropics than that Family. 
In place of the great variety of fruits that we have seen to characterise the Rosacece, 
the Leguminosce take their name from the one type of fruits which prevails, with 
merely trivial variations, throughout the entire Family, viz. a single, superior, 
many-ovuled carpel, becoming generally a dry dehiscent pod or legume. 
Living in every variety of climate and soil, the species in the Family Leguminosce 
include a very great variety of habit of growth, trees, shrubs, lianes, water-plants, 
tendril-climbers, small herbs, xerophytes, etc. One physiological peculiarity, 
apparently universal in the Family, which may well account largely for its success in 
the struggle for existence, is the capacity for utilising the free nitrogen in air by 
means of tubercles on the roots, produced and occupied by symbiotic Bacteria. 
The leaves are, like those of Rosacece, usually scattered and stipulate ; but the 
stipules are more often free, and the leaves themselves nearly always compound. 
The high organisation of the leaf, with stipules, articulations often numerous and 
accompanied by “ sleep ” mechanism, and sometimes tendrils, indicates the advanced 
grade of specialisation of the Family. 
Uniform as they are in their fruit, the members of the Family fall into three 
very “ natural,” i.e. well-marked, Sub-Families in respect of their flower-structure, 
though in all the odd sepal is at the front of the flower {anterior), instead of being, as 
it is in the Rosacece, posterior. The Mimosoidece, including the Acacias, have poly- 
symmetric flowers with small valvate perianths and prominent stamens varying in 
number from four upwards. The Ccesalpinioidece, which include, among well-known 
plants, the Judas-tree {Cercis Siliquastrum Linn6) and the Cassias, have monosymmetric 
flowers, usually with imbricate perianths, conspicuous corollas, and ten stamens ; but 
the corolla is not papilionaceous. These two Sub-Families are mainly Tropical. The 
Papilionatce, the only Sub-Family represented among British plants, all have the 
peculiar arrangement of the petals known as papilionaceous, in which the posterior 
petal, generally the largest and known as the standard, overlaps both the side or 
“ wing ” petals and they in turn each have their other edge over {i.e. external to) an 
edge of one of the two anterior or “ keel ” petals. Whilst the “ claws ” or bases of 
all five petals remain distinct, these two keel petals are more or less united above the 
base by their outer edges. The calyx consists of five sepals united below into a flat 
or convex receptacle, so that the insertion of the petals and stamens is perigynous ; 
