. Bulletin of the British Museum (Natural History) Botany. 88 N. K. B. ROBSON 14). In the more primitive and many relatively advanced species, further branching is also dichotomous ( H. roeperanum, sect. 1. Campylosporus, Fig. 14a), but pinnation often occurs, especially towards the margin ( in species of sect. 9. Hypericum, where it is accompanied by the looping of the laterals on to the midrib or on to each other, Fig. 14b). In foliaceous sepals ( in H. przewalskii, Fig. 14c) a densely reticulate venation is produced; but this is always clearly a development from parallel or dive
. Bulletin of the British Museum (Natural History) Botany. 88 N. K. B. ROBSON 14). In the more primitive and many relatively advanced species, further branching is also dichotomous ( H. roeperanum, sect. 1. Campylosporus, Fig. 14a), but pinnation often occurs, especially towards the margin ( in species of sect. 9. Hypericum, where it is accompanied by the looping of the laterals on to the midrib or on to each other, Fig. 14b). In foliaceous sepals ( in H. przewalskii, Fig. 14c) a densely reticulate venation is produced; but this is always clearly a development from parallel or diverging veins, unlike the reticu- lation in the leaves, which tends to develop from midrib branches (cf. Fig. 10). Thus, in general (and for any given species) the venation of the sepals is at a less advanced stage of evolution than is that of the leaves. Where the sepals are narrow, however, the laterals and branchings may be few or absent, as in narrow leaves (Figs lOh, 14d).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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