COURSE OF THE BUNDLES IN THE STEM. 



241 



If a peduncle is seated in the axil of the leaf it receives two bundles from the stem 

 (de, ik), which usually run separately through one internode, and affix themselves in the 

 next node to the lateral bundles of the next higher trace. In this case the transverse 

 section (Fig, 99) shows eight bundles, or, when the axillary bundles are absent, six bundles 

 arranged in a circle, and with two more in the corners. Variations from this type are 

 brought about by the bundles uniting higher or lower, and by variations of the pectina- 

 tions. The width of the leaf-trace in the first two internodes is 190° to 2 10°. 



II. Leaves alternate, in two rows. Leaf-trace usually of five bundles, the lateral 



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Figs, ioo, joi.— Fcenicutum officinale. Fig. 100. Scheme of the vascular system for leaves with seven bundles, 

 the cylinrlrical surface being reduced to a single plane ; at the level of the figures r, 2, 3 are the nodes. 7n always 

 indicates the, median bundle passing out at the node; / the marginal bundles.— Fig. 101 (40). Transverse section 

 through an internode with arrangement and number of bundles corresponding to that of Fig. 100. i. The bundles 

 of the trace from the next higher leaf, yni its median bundle ; i-f-z the bundle formed from the marginal bundles of i 

 and the median bundle of the leaf next but one above. The bundles alternating with those numbered are the united 

 traces of the two leaves above i ; between the bundles is indicated the cambium zone which connects them. The 

 small circles outside the stronger bundles are the transverse sections of oil passages ; in each of the blunt aisles of 

 the stem is the transverse section of a bundle of fibres having the shape of a segment of a circle. 



bundles of two successive leaves are not completely pectinated. Fitis 'vinifera^ Ampe- 

 lopsh hederacea. 



13. Leaves alternate, in two rows. Leaf-trace usually of five bundles, the lateral bundles 

 of two successive leaves completely pectinated. 



Phaseolus 'vulgarh, Ph. multiflorus — Nageli, /. t. ; Dodel. in Jahrb. f. wiss, Bot, Bd. VIII. 



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