. Bulletin of the British Museum (Natural History) Botany. . Fig. 18 Variation in venation and glandularity of petals in Hypericum (numbers indicate sections); (a) H. stvphelioides (29); (b) H. forrestii (3); (c) H. perforatum (9); (d) H. asperulum (17); (e) H. elodeoides (27) (a, b x 2-5; c x 3'5; d x 4; e x 5). sect. 30. Spachium have only three, unbranched veins. The veins are crowded and little- branched in the morphologically outer part of the petal but more widely spaced and more frequently dichotomising in the inner part (Fig. 18a).* Towards the margin they sometimes form loops or lambd
. Bulletin of the British Museum (Natural History) Botany. . Fig. 18 Variation in venation and glandularity of petals in Hypericum (numbers indicate sections); (a) H. stvphelioides (29); (b) H. forrestii (3); (c) H. perforatum (9); (d) H. asperulum (17); (e) H. elodeoides (27) (a, b x 2-5; c x 3'5; d x 4; e x 5). sect. 30. Spachium have only three, unbranched veins. The veins are crowded and little- branched in the morphologically outer part of the petal but more widely spaced and more frequently dichotomising in the inner part (Fig. 18a).* Towards the margin they sometimes form loops or lambda junctions (Melville, 1969, 1976) with adjacent veins (Fig. 18b-d); but they frequently reach the margin unbranched (Fig. 18b) or (sometimes excepting the midrib) stop short of it without forming a loop or junction (Fig. 18e). The evolutionary progressions in general seem to be: Veins numerous—?few; much-branched—?unbranched; free—"-looped or joined; all reaching margin—?only midrib reaching margin—»-none reaching margin. (e) Glandularity The petal glands in Hypericum are comparable with those of the sepals, except that truly inframarginal glands are rare. When the glands form a distinct peripheral row, they are dark and usually touch or interrupt the margin in some way. Such a row is present in the petals of Santomasia in the form of glandular cilia or sessile glands, sometimes along with a few larger submarginal dark glands (Fig. le). In all other genera of the Hypericoideae, as well as those of the Bonnetioideae, the petal margin is always entire and marginal glands are absent. Their presence in the Hypericeae may therefore be regarded as an advance. Once acquired, however, they can be lost again ( in sect. 3. Ascyreia) and then reacquired ( in *In Archytaea (Bonnetioideae), on the other hand, the petal is symmetrical and the veins are equal and symmetrical also, cf. Maguire (1972 : fig. 2d).. Please note that these images are extracted from scanned
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