244 Transactions. — Botany. 



to receive any — this occurs in Wahlenbergia, Geyitiana, etc., and such flowers 

 are functionally unisexual, and are said to be proterandrous. But all have 

 not this character so fully developed, and every gradation may be noticed 

 from complete proterandry to the opposite extreme. Thus in buttercups, 

 the outer anthers commence to dehisce first, and the process extends from 

 without inwards ; but considerably before the inner anthers have dehisced 

 the stigmas have become viscid. In Epilobium again, at least among New 

 Zealand species, I have never been able to notice any difference of time 

 between the maturing of the anthers and stigmas. Here cross-fertilization, 

 when it takes place, will be chiefly accomplished through the prepotency of 

 the pollen brought from other flowers by insect visitants. But this func- 

 tional separation of the sexes is equally well accomphshed by the opposite 

 arrangement, viz., the maturing of the stigmas first, and the protrusion and 

 dehiscence of the anthers only after the former have been pollinated and are 

 withered up. This is very well exemplified in the various species oiCoriaria 

 (tutu). Such flowers are called ju?-o^e?-o(/^?jo»s, while the tevm. dicJioi/amy is 

 applied generally to the maturing of the sexual whorls at different times. 



Another means of accomplishing the same end, viz., cross-fertilization, 

 is attained by the occurrence of two or more forms of flowers in the same 

 species (heterostylism). Thus some species of Primula are dimorphic, 

 having two forms, one with long style and short stamens, the other with 

 short style and long stamens. Some few flowers are even trimorphic. For 

 a more complete description of these forms I must refer to Darwin's work 

 already quoted. I have not detected distinct heterostylism in any New 

 Zealand plant as yet, though in some Pimeleas, Asperula, etc., I have found 

 something very like it. Special structures of the perianth, or of the sexual 

 whorls, serve to prevent self-fertilization among certain flowers, and to 

 ensure their proper pollination, but these are so numerous and varied as to 

 obtain only a passing notice here. I have detailed m the body of this 

 paper the most conspicuous of these modes, as they are exemplified among 

 New Zealand plants. 



It is worthy of notice that entomophilous plants are usually furnished 

 with flowers possessing, more or less markedly, the following characters : — 

 (1.) Conspicuous appearance, attained in a variety of ways, viz., by individual 

 size as in Clematis indivisa ; aggregation into more or less dense clusters as 

 in Rubus aiistralis, and many of the Composite, etc. ; or, brilliancy of colour 

 as in our iron-wood, (Metrosideros lucida). (2) Fragrance. (3) Honey. 

 Sometimes all three charact^istics are present, as in certain of the wild 

 roses of Europe, but as a general rule a principle of economy prevails, so 

 that if any one attraction is present to a great extent, the others are usually 

 wanting. Thus Clematis indivisa has very conspicuous flowers, but they 



