THE MAKING AND UN3IAKING OF FLOWERS. 



115 



THE MAKING AND UNMAKING OF FLOWERS. 

 Lecture delivered February 26, 1901, 

 By Rev. Professor G. Henslow, M.A., F.L.S., V.M.H., &c. 



Part I. — The Making. 



If we ask — What were the first flowers like ? it is not easy to reply ; for 

 plants are so much more perishable than shells and bones that the 

 destruction of primitive forms of vegetation has been very much 

 greater than that of animals. Still we know that some of the earliest 

 land-plants were Cryptogams. Such were the allies of our existing Ferns, 

 Club-mosses, and Horsetails ; for these constituted the larger portion of 

 the forests which contributed their remains to form our coal beds. 



Now modern researches have discovered points of affinity between 

 certain Gymnosperms (represented in these islands by the Scotch Fir, 

 common Juniper, and Yew only) and the above-mentioned Cryptogams ; 

 so that the bridge from flowerless to flowering plants undoubtedly existed 

 between these two groups of plants ; but we do not know where to look 

 for the site of the actual bridge itself. 



Our starting point is, therefore, Gymnosperms* i.e. " naked-seeded 

 plants," forming a sub-class of Dicotyledons ; and the first question is — 



ah a b 



Fig. 34. — a, Ovule, half grown, with Fig. 35. — «, Stamen ; 6, carpellary scale 



developing cup, bracts seen below; of Scotch Fir, with two pendulous 



b, ripe seed included within the ovules, 

 scarlet cup. 



How did these naked-seeded trees and shrubs pass into others u-ith a 

 pistil in which the seed is enclosed, and therefore called Angiospcrms, i.e. 

 " seeds in a vessel " ? 



Let us take the simplest case possible, the female flower of the Yew 

 (fig. 34). It consists of an ovule only. This constitutes the whole flower. 

 It is at first protected by a number of minute, overlapping and roundish 

 little bracts ; biit there is no trace of a carpel of any sort. A succulent 

 cup grows up and nearly conceals the naked seed when ripe. 



In the Juniper, the Fir tree (fig. 35), and the Cypress (tig. 36), we find an 

 open scale associated with one, two, or several ovules respectively. It is 

 sometimes called a " carpellary " scale, but whether justly so or not is open 

 to question. In Cv/crts (fig. 37) there occur small leaves with ovules on their 

 margins. 



* This embraces three families only — Gnctacccv, with 3 genera ; CycadacC(.r,v>iih 0; 

 and Conifercc, with 32. 



I 2 



