A NGIOSPERMS. 411 



of Amorpha, Salix, Rudbeckia, Lupinus, Veronica, Digitalis, Orchis, Delphinium. 

 But there are other inflorescences in which the shoot is formed immediately^after its 

 subtending leaf, so that no rudiment of a leaf appears beneath the apex of the mother-shoot 

 above the youngest shoot, as in Plantago, Orchis, Epipactis-, sometimes the shoot and 

 the leaf are formed simultaneously, as in the Gramineae, Cytisus, Trifolium, Orchis, 

 Plantago, Ribes ; or lastly the axillary shoot is formed before its subtending leaf, in 

 which case the leaf attains only a slight development, there being an indication only of 

 its presence, as in Sisymbrium, Brassica and other Cruciferae, Umbelliferae, Anthemis, 

 Valeriana, the Asclepiadeae, Bryonia, Cucumis ; or the subtending leaf is not de- 

 veloped, as in many Cruciferae (Fig. 338), Compositae, Gramineae, Umbelliferae, Papilio- 

 naceae, Boragineae, Solanaceae, Hydrophyllaceae, Saxifragaceae, Potamogeton. In all 

 these inflorescences we find therefore the youngest flower-buds nearer the apex of the 

 parent-shoot than any leaf, in so far as these have been formed at all ; but the branching 

 must not therefore be explained as a dichotomy of the parent-shoot ; this only takes 

 place when the formation of a shoot occurs so near the apex and with so much vigour 

 that a continuation of the previous direction of growth of the parent-shoot is rendered 

 impossible, and the apex divides into two or more apices, as happens according to 

 Warming in Hydrocharis, Vallisneria, the Asclepiadeae, and some Cucurbitaceae 1 . 

 That there is a connection between this tendency to dichotomy in plants in which the 

 vegetative portion of the plant shows axillary branching and the suppression of the 

 leaves in the inflorescences is to be inferred also from the fact, that the tendrils of 

 Vitis and Cucurbita, in which also there is only a rudimentary formation of leaves, 

 show the same inclination to dichotomy. 



The axillary shoots of the vegetative region are usually so placed, that they spring at 

 the same time from the base of the leaf and from the tissue of the stem ; but it some- 

 times happens that the shoot moves quite on to the stem and therefore is detached 

 from the leaf. In the floral region on the other hand it is not rare for the axillary shoot 

 (the flower) to spring altogether from the leaf, as in Hippuris, Amorpha, Salix nigri- 

 cans ; but if the bract is formed later than the shoot (flower), it can spring from it, and 

 in that case is no longer in direct connection with the parent-shoot, but appears to be 

 the first (lowest) leaf of the lateral shoot ; this is the case according to Warming in 

 Anthemis, Sisymbrium, and the Umbelliferae, and to a lesser extent in Papilionaceae, 

 Orchideae, Valerianeae, etc. These circumstances are usually most apparent in the 

 earliest stages of development ; the bract is often found moved more or less high up 

 the stem in the fully developed state of the plant, as in Thesium ebracteatum, Samolus 

 Valerandi, the Boragineae, Solanaceae, Crassulaceae, Spiraea, the Loranthaceae, 

 Ipomaea bona nox, Agave Americana, Ruta, Paliurus, Tilia in which this is true of 

 the large bract of the inflorescence, and others. 



Bracteoles. The formation of the flower on the floral axis is usually preceded by the 

 appearance of certain foliar structures, which cannot be regarded as forming part of 

 the flower ; they are known as bracteoles, and may be compared with the first scale-like 

 leaves formed on rudimentary vegetative shoots. In Monocotyledons the bracteole is 

 placed on the side of the shoot which is towards the parent-shoot, the dorsal side. 

 Dicotyledons have usually two bracteoles placed right and left on the lateral faces of the 

 branch ; Monocotyledons in exceptional cases have two bracteoles and Dicotyledons 

 one. The bracteoles are omitted in the diagrams in this work, because these are 

 intended to show only the relative position of the parts of the flower. 



Relative position and number of the parts of the flower 2 . As the forms of the 



1 The statements of Warming respecting dichotomy in the inflorescence of the Boragineae and 

 others, at least in the majority of cases, are incorrect. 



2 [If in each of the three- outer series of organs of the flower (calyx, corolla and androecium) there 

 are five leaves or their number is a multiple of five, the flower is said to be pcntamerous ; similarly 

 the terms bimerous, trimerous, etc. designate flowers in which the whorls of these organs have two 



