MONOCO TVLEDONS. 



621 



produce from generation to generation thicker axes, larger leaves, and stouter 

 roots, until at length a condition again results in which each successive generation 

 of shoots produces others of equal strength. If the portions of the axes of the 

 shoots beneath the points where the shoots of the next order arise are persistent, 

 sympodia arise (as represented in Fig. 143); but frequently each shoot entirely 

 disappears after producing one of the next order, as for instance in our native 

 tuberous Orchids (Fig. 158), or in the Crown-Imperial (Fig. 421), or Autumn 

 Crocus (Fig. 422) \ 



The normal Mode of Branching of Monocotyledons is always monopodial 

 and usually axillary ^ ; a bud is generally formed in the axil of each leaf, but often 

 does not unfold, so that the number of branches visible is often less than that 

 of the leaves (as in Agave, Aloe, Draccena, Palms, many Grasses, &c.). But some- 

 times several buds are formed in the axil of a leaf, and if the insertion of the 

 leaf is broad these are placed side by side, as occurs in many bulbs (Fig. 130). 



Fig. 421. — Bulb of Fritillaria imperialis in November : A longitudinal section of the whole bulb reduced, z z the 

 coalescent lower portions of the bulb-scales, bb their free upper portions; the scales enclose a cavity /which contains the 

 decayed flower-stem : next year's bud is formed in the axil of the innermost scale ; its first leaves will form the new bulb, while 

 its axis will develope into the flower-stem ; the root w springs from the axis of this bud. B longitudinal section of the apical 

 region of next year's bud, s apex of the stem, bb' b" youngest leaves. 



In Musa a number of flowers even stand side by side in the axil of a bract, 

 and in Musa Ensete two rows one over the other. In the Spadiciflorae the bracts 

 are often absent ^ and the ebracteate flowers stand on the rachis of the inflorescence, 

 but are distinctly lateral in their origin. This is also the explanation of the 

 branching of Lemna, which does not in general form any foliage-leaves, but 

 the vegetative body of the plant consists of disc-like or swollen portions of the 

 axis containing chlorophyll which branch laterally out of one another, and are 

 connected together only by slender stalks, or soon separate. The plane of rami- 

 fication coincides with the surface of the water on which they float; each shoot 



^ Further details of the great variety of modifications of these processes of growth will be found 

 in Irmisch, Knollen und Zwiebelgewachse (Berlin 1850), and Biologic und Morphologic der 

 Orchideen (Leipzig 1853). 



^ According to Magnus (Bot, Zeitg, 1869, p, 770) the flower of Naias occupies exactly the place 

 of the first leaf of a branch; but it appears from p. 771 as though the flower and the shoot that 

 i)ears it were the bifurcations of a dichotomy. 



^ Compare under Dicotyledons, p. 638. 



