PDF - Wallace Online

TROPICAL NATUREdetails of these adaptations we must refer the reader to theworks of Darwin, Lubbock, Herman Miiller, and others. Wehave here only to deal with the part played by colour, andby those floral structures in which colour is most displayed.Attractive Odours in FlowersThe sweet odours of flowers, like their colours, seemto have been developed as an attraction or guide to insectfertilisers, and the two phenomena are often complementaryto each other. Thus, many inconspicuous flowers, like themignonette and the sweet -violet, can be distinguished bytheir odours before they attract the eye, and this may oftenprevent their being passed unnoticed; while very showyflowers, and especially those with variegated or spotted petals,are seldom sweet. White, or very pale flowers, on the otherhand, are often excessively sweet, as exemplified by thejasmine and clematis and ; many of these are only scented atnight, as is strikingly the case with the night-smelling stock,our butterfly orchis (Habenaria chlorantha), the greenishyellowDaphne pontica, and many others. These whiteflowers are mostly fertilised by night-flying moths, and thosewhich reserve their odours for the evening probably escapethe visits of diurnal insects, which would consume theirnectar without effecting fertilisation. The absence of odourin showy flowers, and its preponderance among those thatare white, may be shown to be a fact by an examination ofthe lists in Mr. Mongredien's work on hardy trees and shrubs. 1He gives a list of about 160 species with showy flowers, andanother list of sixty species with fragrant flowers ;but onlytwenty of these latter are included among the showy species,and these are almost all white flowered. Of the sixty specieswith fragrant flowers, more than forty are white, and anumber of others have greenish, yellowish, or dusky andinconspicuous flowers. The relation of white flowers tonocturnal insects is also well shown by those which, like theevening primroses, only open their large white blossoms aftersunset, while most of the yellow species remain open all day.The red Martagon lily has been observed by Mr. Hermanx Trees and Shruts for English Plantations, by Augustus Mongredien.Murray, 1870.