Vegetable Physiology. S75 



upon practice chiefly through affording instructive illustrations 

 of phenomena of reproduction occurring in an analogous manner 

 in the higher plants, where tliey are less accessible to direct ob- 

 servation. 



The higher of the two groups founded on the characters of 

 the vegetative system comprehends all plants possessing a stem, 

 or axis^ bearing leaves above and roots below, presenting there- 

 fore two diametrically opposite directions of growth. The dis- 

 tinctive name of Curmophytes has been applied to these, from the 

 Greek word kormos a trunk or stem, and phyton a plant ; the 

 term Vascular plants, as contrasted with Cellular plants, is likewise 

 applicable to all but the lowest orders. In the simplest members 

 of this sub-kingdom the fibro- vascular structures are present, but 

 represented by elementary organs presenting little variety of 

 conformation ; thus in the Mosses they constitute a simple fibrous 

 cord running through the centre of the stem, giving off branches 

 which sometimes run into the blades of the little leaves, but more 

 frequently are confined to the stem, so that the leaves are mere 

 cellular plates like the fronds of the stemless plants. In the 

 Ferns and allied plants there is a great advance, tlie general cha- 

 racters of the stems and leaves approaching those of the flowering 

 plants ; but the inferiority of organization indicated by the 

 absence of flowers, and the intimate connexion of the reproduc- 

 tive structures with vegetative system (evident in the formation 

 of the spores on the ordinary leaves of Ferns), correspond to a 

 much slighter diversity and complexity in the conditions and 

 arrangement of the fibro-vascular elementary tissues. 



In the Flowering-plants, In the two large classes called the 

 Monocotyledons and Dicotyledons, the different plans of arrange- 

 ment of the fibro-vascular structures cause a totally different 

 mode of growth of the stems, forming perhaps the most strongly- 

 marked of the characteristics by which these classes are dis- 

 tinguished. 



As in tlie Thallophytes, however, the most important diver- 

 sities of the sub-kingdom of Cormopliytes lie in the mode of 

 development and arrangement of the reproductive organs. In 

 the progressively higher orders these become step by step extri- 

 cated from their connection with the vegetative system, until In 

 the Flowering-plants we find the organs which produce the repro- 

 ductive bodies {seeds) associated with a complicated collection 

 of specially-metamorphosed organs (sepals, petals, stamens, &c.), 

 while the germs produced are no longer thrown off as simple 

 cellular bodies, but remain dependent upon and nourished by 

 the parent plant until they have acquired their own stem, leaves, 

 and root — that organization, in fact, Avhich distinguishes the 

 vascular stem-forming from the cellular or stemless plants. 



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