Nature and development of plants . ause an exces-sive transpiration. Possibly these plants are not able to absorbwater rapidly owing to the limited amount of conducting tissuesand to the exclusion of the atmosphere by the water which sur-rounds the roots (see pages 40, 46), consequently they are atthe same disadvantage and require the same protective devicesas plants living in arid localities. Order 4. Lycopodiales. The Club Moss Ferns 115. General Characters.—The members of this group arepopularly known as the club moss ferns owing to their smallmoss-like leaves and the arrangement of the spo
Nature and development of plants . ause an exces-sive transpiration. Possibly these plants are not able to absorbwater rapidly owing to the limited amount of conducting tissuesand to the exclusion of the atmosphere by the water which sur-rounds the roots (see pages 40, 46), consequently they are atthe same disadvantage and require the same protective devicesas plants living in arid localities. Order 4. Lycopodiales. The Club Moss Ferns 115. General Characters.—The members of this group arepopularly known as the club moss ferns owing to their smallmoss-like leaves and the arrangement of the spore-bearing leavesinto club-like strobili or cones (Fig. 236). The gametophyte orsexual generation is also suggestive of the mosses. Particularlyis this true of the male gamete, which is small and apparentlybiciliate (Fig. 240). 3io THE LYCOPODIALES The Lycopodiales are largely tropical, though a small numberof forms are of common occurrence in temperate regions. Thestems are erect or creeping and rather small, but owing to their. Fig. 236. A common club moss fern, Lycopodiwm annotinum, withcreeping stem and erect branches covered with small moss-like leaves:s, strobilus; r, roots.—H. O. Hanson. prolonged growth and extensive branching they often form con-spicuous and attractive colonies. The tissues of the stem donot materially differ from those of the common fern, though thevascular bundles are centrally placed and often appear as radiat-ing plates (Fig. 237). The work performed by the leaves, asin the Equisetales, is usually of two kinds, namely, photosynthe-sis by the green foliage leaves and spore production by the leavesthat usually form strobili at the tips of certain branches. But asingle sporangium is associated with each of these sporophyllsI Fig. 239). DEVELOPMENT OF PLANTS 311 The club moss ferns are a much -larger group than the Equise-tales, but like the latter group, they are a remnant of a highlydeveloped and widely distributed race. Fossil remains indicateth
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