16.] CHAPTER II. SPECIAL MORPHOLOGY O*' THE MEMBERS. 77 



When the rhachis bears a single terminal flower it is commonly termed the 

 peduncle of the flower ; when the rhachis is branched, the branches may be so 

 short that tbeir flowers appear to spring directly from the rhachis, and the 

 flowers are said to be sessile ; when the branches are longer and bear terminal 

 flowers, they are termed pedicels, and the flowers are said to be pedicillate. 

 For further details as to inflorescences, see Part III. 



When no sporophylls are present, the form of the flower is ex- 

 tremely simple. When sporophylls are present, the form of the 

 flower varies with the degree of elongation attained by the termi- 

 nal internodes of the axis. When they elongate to some extent, 

 the flower forms a cone, as in Equisetum, Lycopodium, Selaginella, 

 Pinus. When they remain short, as generally in Angiosperms, 

 the apex is more or less broadened, forming a flattened, depressed, 

 or shortly conical torus on which the sporophylls and the perianth, 

 leaves are borne. The various forms of flowers are described in 

 detail in Part III. 



In heterosporous plants it is commonly the case that the two 

 kinds of sporangia are borne together on the same axis of the 

 sporophore ; that is, they are included in the same flower (e.g. Sela- 

 ginella, most Angiosperms), which is then said to be ambisporangi- 

 ate; but they are frequently confined to distinct axes, as in the 

 Gymnosperms, and in some Angiosperms (e.g. Beech, Birch, Oak, 

 Walnut, etc.) ; these distinct flowers are said to be monosporangiate, 

 and are distinguished, according to the kind of sporangia which 

 they respectively bear, as microsporangiate or macrosporangiate ; in 

 some cases one individual bears exclusively microsporangiate, and 

 another exclusively macrosporangiate flowers, as in the Hemp, the 

 Yew, etc. 



(c) The Sporophylls. In many cases, most Ferns and Lycopo- 

 dinae, for example, the sporophylls are similar to the foliage- 

 leaves, differing only in that they bear sporangia; but more com- 

 monly the sporophylls are distinguished by some peculiarity in 

 form or structure. Thus in the Flow,ering Fern (Osmunda regal! s) 

 the sporophylls differ from the foliage-leaves in that no green 

 leaf -tissue is developed in them. In Botrychium, Ophioglossum, 

 and the Hydropteridese (Rhizocarpse), the sporophyll is a branch 

 or segment of a foliage-leaf, characterised by a peculiar form and 

 by the absence of green leaf-tissue. In Mar^ilea and Pilularia the 

 sporophyll forms a hollow capsule, enclosing the sporangia. In 

 Equisetum, the sporophyll is a peltate scale bearing the sporangia 

 on its inner or under surface. In the Gymnosperms the sporo- 



