BUNDLE-SVSTEM IN THE LEAVES. 297 



been above described (pp. 257-259) in Calycanthus and Melastomacese. Hanstein 

 found them in Sambucus, in species of Valeriana, Centranthus, Valerianella ; Scabiosa, 

 Knautia, Succisa, Dipsacus ; Dahlia, Bidens cernua, and tripartita ; Guizotia oleifera ; 

 and Nageli in Humulus. In most plants with opposite leaves, e. g. the Labiatse, 

 Asclepiadeae, Caryophyllacese, Caprifoliacese excepting Sambucus, many Compositae 

 and others enumerated by Hanstein, the transverse girdles do not occur. 



Branch bundles passing down through the cortex may here be mentioned, and 

 have already been described above for many Cyatheaceae. Also in the strict sense 

 the medullary bundles of these latter Ferns belong to this category, as being ' appen- 

 dices ' which run downwards from the bases of the leaves. Among the Monocoty- 

 ledons no examples belonging strictly to this series are known, still the bundles 

 running through the cortex, as described above for Bromeliaceae and Palms, correspond 

 in their course to some extent to those under discussion. The same may be said of 

 the above-described cortical bundles of Melastomaceae and Calycanthus. Among 

 the Dicotyledons, however, branches passing downwards from the node through the 

 cortex occur elsewhere ; in the first place in the foliaceous corners of the so-called 

 winged stems, e. g. in species of Lathyrus (L. silvestris, latifolius, Nissolia, &c.), 

 secondly, and in the most striking manner, in many (but by no means all) succulent 

 plants : Salicornia, species of Mesembryanthemum, Cacteae. The course and 

 ramification of the bundles in these cases and in the winged corners closely resemble 

 that to be described in the leafy expansions, the cortex here assumes completely the 

 anatomical (and physiological) properties of foliar expansions. 



In the species of Salicornia ^ the short scaly leaves are arranged in decussate 

 pairs. One bundle, which splits up immediately at its point of exit into three branches, 

 passes from the node into each leaf: of these a single median one runs to the apex of 

 the leaf-scale, and a lateral one on either side passes perpendicularly downwards into 

 the cortex. These branches, of which there are six for each pair of leaves, give off 

 throughout their whole course numerous ramifications, which anastomose frequently in 

 a reticulate manner. From the apices of the leaves downwards the cortex of the whole 

 internode, which attains a length of 2cm, is traversed by a tubular network of bundles, 

 which is closed (not interrupted as stated by Duval), and which ceases immediately 

 above the next lower node, without any connection with that which there arises. In 

 many species of Mesembryanthemum, e. g. M. imbricatum, M. crystallinum, &c., but 

 by no means in all species of the genus, thin branch bundles, divided into reticulately 

 anastomosing branches, pass downwards from the node into the cortex ; here again 

 they do not reach the next lower node. In Cacteae, Epiphyllum truncatum, species 

 of Cereus, Mamillaria, the above-mentioned (p. 261) Rhipsalidaceae ^ &c., reticu- 

 lately connected branches come off from the main bundles, which run to the apex 

 of the rudimentary leaves, and pass through the cortex, forming a continuously 

 anastomosing network between the neighbouring main bundles. 



The bundles, which enter stipules, and other appendages of the base 0/ the leaf 

 which often have a glandular surface, usually arise as branches from those which 

 enter the main leaf (e. g. Prunus, Passiflora, Tropaeolum, Medicago, Liriodendron ^, 



' Diival-Jouve, I.e. (see above, p. 226). 

 - Vochting, /. c, 2 Nageli, Beitr. /. c. 



