Nature and development of plants . Fig. 120. Three of the larger brown algae: A, Lominaria. B, Lcssonia. C, Macrocystis. DEVELOPMENT OF PLANTS 185 (b) The Coarser Brozvn Algae, the Kelps.—This latter condi-tion is well illustrated in the kelps, plants related to Ectocarpus,which include the largest and most highly organized forms ofall the algae. Indeed some of these forms are quite comparablein size with our shrubs and trees. The Laminarias (Fig. 120, A)of our Atlantic coast have stalked blades ten to twenty feet great bladder kelps of the Pacific, Nereocystis and Macro-cystis, attai
Nature and development of plants . Fig. 120. Three of the larger brown algae: A, Lominaria. B, Lcssonia. C, Macrocystis. DEVELOPMENT OF PLANTS 185 (b) The Coarser Brozvn Algae, the Kelps.—This latter condi-tion is well illustrated in the kelps, plants related to Ectocarpus,which include the largest and most highly organized forms ofall the algae. Indeed some of these forms are quite comparablein size with our shrubs and trees. The Laminarias (Fig. 120, A)of our Atlantic coast have stalked blades ten to twenty feet great bladder kelps of the Pacific, Nereocystis and Macro-cystis, attain great dimensions, the latter genus reaching a lengthof 500 to 900 feet and Lessonia with trunk-like stems and leaf-like segments forms veritable submerged forests in the Ant-arctic Ocean (Fig. 120, B, C). These highly organized plantshave apparently lost or failed to develop a sexual method ofreproduction and depend entirely upon the formation of zoo-spores for their Fig. 121. Two common forms of the Fucaceae: A, Sargassum, thestem-like axis bearing air sacs, s, and leaf-like organs; g, reproductivebranches. B, Fucus—s, air sacs; g, reproductive branch. C, young plant. The rock weed or bladder wrack (Fucus) and the gulfweed (Sargassum) are representatives of a group, Fucaceae,that contain the most specialized of the brown algae (Fig. 121). 186 STRUCTURE OF FUCUS The Sargassum with its stem and leaf-like organs which maybecome modified into air sacs and reproductive organs bears theclosest external resemblance to the higher plants of any of thealgae (Fig. 121, A). It forms the major portion of that floatingvegetation in the Atlantic known as the Sargasso Sea. Thebladder wracks may be found firmly attached to the rocks bydisc-like holdfasts in almost all colder, temperate and northern h-cr
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