Page:The Journal of Indian Botany.djvu/156

126 what has been taken to be Wight's :H. hirsutus has rather broader leaves than Wight's illustration, (Ic. Pl. In. Or. t. 2067) shows but is probably the same species, and the illustration might have been drawn from my plant. (Comp. the plate opposite). It would seem therefore that Wight's H. hirsutus and perhaps also H. glaber, has orange flowers on the lower slopes and blue flowers on the higher, and that they are two varieties a glabrous and a hairy of one species. A change from pink or purple to blue is common enough but orange and blue are not as a rule I believe, interchangeable, a blue colour being usually in the cell sap, but an orange in plastids. Possibly we have in these four plants two pairs of Mendelian allelomorphs segregating; hair and their absence, and orange and blue colours. Both forms were abundant where I found them, and growing side by side.

It would be interesting therefore to know whether there are any cases known of a species having blue flowers in one place and orange flowers in another.

The flowers of Hydnocarpus alpinus Wtk are typically dioecious. Recently I found near Coonoor a single male flower on a female tree, with pistillate flowers and fruits above and below on the same branch. Such an occurrence is probably not uncommon, though seldom recorded. Davy and Gibson described, the occurrence of both sexes on the same plant of Myrica Gale a typically 'unisexual' dioecious species, and what, was more interesting, observed a change from maleness to femaleness between one year and the next on more than one plant.

Ever since the discovery of chromosome reduction we have been compelled to consider higher plants and ferns as never really sexual at all, sex appearing only in the last divisions of the cells which produce the pollen grains and ovule respectively. But where the flowers are unisexual the visible ' sex' may be dependent on external conditions, and is known to be affected sometimes by parasites. The object of this note is to call attention to this, for in India we have many plants with unisexual flowers e.g. spp. of sterenlic, Terminalia, Piper, Myristica and observations of these, from year to year, by those in a position to make them, might lead to the discovery of the conditions which affect 'sex' (though if as seems likely sex is a Mendelian character, only in heterozygous individuals) or in the relative numbers of male and female flowers, with results perhaps of both scientific and economic importance.