434 



FOURTH GROUP.— SEED-PLANTS. 



axil of a bract, and in Mum Enscte two rows even one above the other. In the 

 Spadiciflorae the bracts are often wanting, and the flowers grow without them from 

 the axis of the inflorescence, but are nevertheless of distinctly lateral origin. The 

 branching also of Lemna, where there are no foliage-leaves, is lateral ; the vegetative 

 body consists in this plant of disc-shaped or much swollen portions of the axis which 

 are rich in chlorophyll and grow laterall}' from one another, and are connected together 

 only by slender stalks or soon separate ; the plane of branching coincides apparently 

 with the surface of the water on which the plants float ; each shoot produces only one 



Fig. 359. Germination of Apoiiogtton distacliyuin ; hw primary root, c cotyledon, h first leaf, mi first secondary root 

 springing from the stem, which soon thickens into a tuber k, and developes fresh secondary rcots w, w ; to the left the 

 youngest, to the right the oldest stage. After Dutailly. 



or two lateral shoots which are originally dorsal but become afterwards lateral \ and 

 the branching is therefore distinctly cymose-sympodial or as in Lemna trisiilca 

 dichasial. 



Besides the formation of shoots by the branching of the axis, adventitious shoots 

 also are occasionally formed on the leaves and fulfil the part of gemmae, as in 

 Hyacinihus Pouzolsii and on the margins of the leaves of some Orchideae according to 

 Dofl. The large gemmae which appear very regularly on the leaves of Atheruriis 

 ternatiis, one of the Aroideae, should be specially mentioned ; they grow at the point 

 of union of the leaf-sheath and the stalk, and at the base of the lamin'a ; but the small 

 bulbs on the aerial stems of LiJium bulbi/enun are normal axillary shoots, as are 



' The shoots grow from the upper (dorsal) side of the axis that bears them, but are at an early 

 period enclosed in a pocket by the luxuriant growth of the axis, and moved into an apparently 

 lateral position. 



