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Show 400 ANEMOPHILOUS PLANTS. CHAP. X. in the spring, we should not falsely a?cuse ~ature of wasteful expenditure, though comparatively httlo fruit iR produced in the autumn. Anenwphilous Plants.-The nature and relations of plants which are fertilised by the wind have been admirably discussed by Delpino* and H. Muller; and I have already made some remarks on the structure of their flowers in contrast with those of ento1nophilous species. There is good reason to believe that tho first plants which appeared on this earth were cryptogamic; and judging from what now occurs, the male fertilising element must either have possessed the power of spontaneous movement through the water or over damp surfaces, or have been carried by currents of water to the fe1nale organs. That some of the most ancient plants, such as ferns, possessed true sexual organs there can hardly be a doubt; and this shows, as I-Iildebrand remarks,t at how early a period the sexes were separated. As soon as plants became phanerogamic and grew on the dry ground, if they were ever to intercross, it would be indispensable that the male fertilising element should be transported by some means through the air ; and the wind is the simplest means of transport. There must also have been a period when winged. insects did not exist, and plants would not then have been rendered entomophilous. Even at a somewhat later period the more specialised orders of the Hymenoptera, * Delpino, 'Ult. Osservazioni sulla Dicogamia,' part ii. fasc. i. 1S70; and 'Studi sopm 1m Lignaggio anemofilo,' &c. 1871. H. Muller, 'Die Befruchtung,' &c. pp. 4:12, 442. Both the e authors remark that plants must luwe beeu allemopl1ilous before they were entomophilous. II. MUller further discusses in a very interesting manner the steps by which untomophilous flowers became nectarif'erous and gradually acquired their present stnJctl:re through successi ,.e benefiCial changes. . t 'Die Gescldechter-Vertheil-ung,' 1867, pp. 84-90. • CHAP. X. . ANEMOPHILOUS PLANTS. 401 Lepidoptera, and Diptera which are n h' fl d · h ' ow c Ie y con-cerne Wit the transport of pollen d'd t · . - ' I no exist Therefore the earhest terrestrial plants k t · . nown o us na:rp.ely, the Oonlferm and Oycadim no doubt ' h ·1 · ' were ane-mop I ous, hke . the existing species of these same ~ groups. A vestige of this early state of th' · l'k ' h Ings IS I ewise s o':n by some other groups of plants which ~re anemoph1lous, as these on the whole stand lower In the sc~le than entomophilous species. There ~s no great d~fficulty in understanding how au an~mophilous pla~t might have been rendered entomophllous. Pollen Is a nutritious substance and would soon. have been discovered and devoured' by insects . and .If any adhered to their bodies it would have bee~ earned from the anthers to the stigma of the same flower, or from one flower to another. One of the chief c. h.a ra.c terihs tics of the pollen of anemophilous pian 't s, IS Its Inco erence; but pollen in thi~ state can adhere to the hairy bodies of insects, as we see with some Leguminosm, Ericacem, and Melastornacem. We have ~o~ever~ better evidence of the possibility of a tran~ siti~n. of the above kind in certain plants being now ~~rtllised partly by the wind and partly by insects. .Ihe c~mmon rhubarb (Rheum~ rhaponticum) is so far In. an Inter~ediate condition: that I have seen many Diptera sucking the flowers, with much pollen adherinO' to their bodies ; and yet the pollen is.. . so incoheren f, that clouds of it are emitted if the plant be gently sh.aken on a sunny day, some of which could hardly fall to fall on the large stign1as of the neighbouring flowers. According to Delpino and I-I. Muller,* some species of Plantago are in a similar intermediate condition. * 'Die Befruchtung,' &c. p. 34-2. 2 D |