ANGIOSPERMS. 
599 
part of which — the leaf, — or the other part — the branch, — may be developed earlier 
than the other or simultaneously with it, or more or less completely than it. It is 
evident in the vegetative region that the subtending leaf always arises first, and de- 
velopes more actively, to begin with at any rate, than the corresponding branch which 
only becomes apparent when one or more young leaves have arisen above the leaf 
in question. (Figs. 129, 131.) In many inflorescences the development of the leaf 
precedes that of the axillary branch by a much shorter interval, as in the spikes and 
racemes of Amorphay Salix, Rudbeckia, Lupinus, Veronica, Digitalis, Orchis, Delphinium. 
In the development of other inflorescences the axillary branches are formed immediately 
after their subtending leaves, so that no rudimentary leaf intervenes between the apex 
of the shoot and the youngest axillary branch [Plantago, Orchis, Epipactis). Sometimes 
leaf and branch arise simultaneously, as in the Graminese, Cytisiis, Trifolium, Orchis, 
Plantago, Ribes. Or again, the axillary branch is formed first, before its subtending 
leaf, in which case the leaf attains only a slight development, its presence being merely 
indicated as in Sisymbrium, Brassica and other Cruciferae, Umbelliferae, Anthemis, 
Valeriana, Asclepiadeae, Bryonia, Cucumis. Or the subtending leaf may not make its 
appearance at all, and no bracts are developed, as in many Cruciferae (Fig. 132), 
Gompositae, Graminese, Umbelliferae, Papiiionaceae, Cucurbitaceae, Asperifolieae, Solaneae, 
Hydrophylleae, Saxifragese, Potamogetoneae. In all these inflorescences the youngest 
buds are nearer to the apex of the parent shoot than any foliar organs in so far as these 
have been developed, but the branching must not on this account be regarded as 
dichotomous. A dichotomy of the parent shoot only takes place when a vigorous 
branch is developed so near to the apex that a continuation of the direction of growth of 
the shoot is rendered impossible, its apex apparently dividing into two or more apices. 
According to Warming this is the case in Hydrocharis, Vallisneria, the Asclepiadeae, the 
scorpioid cymes of the Solaneae, Asperifolie^, Hydrophylleae, Cistaceae, and many 
Gucurbitaceae. This tendency to dichotomise shown by plants the vegetative parts of 
which branch in a lateral axillary manner is doubtless connected with the suppression 
of the development of leaves in the inflorescences, and this is confirmed by the fact that 
the tendrils of Vitis and Cucurbita, on which the development of leaves is rudimentary, 
exhibit the same tendency. 
The axillary branches of the vegetative region are usually so placed that they arise 
both from the basis of the leaf and from the tissue of the stem ; but it sometimes 
happens that the branch is entirely transferred to the stem and becomes isolated from the 
leaf. In the floral region, on the other hand, it not unfrequently happens that the axillary 
branch (the inflorescence) arises solely from the leaf, as in Hippuris (Fig. 119), Amorpha, 
Salix nigricans. If, however, the subtending leaf (bract) is developed later than the axil- 
lary branch (inflorescence), it may arise from it, so that the leaf has no direct connection 
with the parent shoot, but appears to be the first lowest leaf of the lateral branch ; this 
is the case, according to Warming, in Anthemis, Sisymbrium, Umbelliferae, and to a slight 
degree in Papiiionaceae, Orchideae, Valerianeae, and others. These relations are usually 
evident at the earliest stage of development, but frequently the subtending leaf is found 
upon the axillary branch in the mature condition, as in Thesium ebracteatum, Samolus 
Valerandi, Boragineae, Solaneae, Grassulaceae, Spircea, Loranthaceae, Ipomcea bona nox, 
Aga've americana, Ruta, Paliurus, Tilia (in which this applies to the large bract of the 
inflorescence), and others. 
3. Number and Relati-ve Position of the Parts of the Flovjer'^. Just as the forms of 
branching of the inflorescence are usually diff'erent from those of the vegetative stem, 
the arrangement of the leaves of Angiosperms is also usually different on the shoot which 
constitutes the flower from that on other parts of the same plant. The cessation of 
the apical growth of the receptacle, its great increase in breadth, or even hollowing out, 
before and during the time when the perianth and the sexual organs are being formed, 
[See Eichler, Bliithendiagramme.] 
