596 



BOTANY 



PART II 



foliage and seed are poisonous, but the aril, which induces birds to distribute the 

 seed, is harmless. 



Family Pinaceae. This family includes the most important Coniferae, and on 

 grounds of differences in leaf arrangement and in the position of the ovules is 

 divided into two sub-families. The forms with the leaves opposite or in whorls 

 are included in the Cupressineae ; they also have the ovules erect. All the forms 

 with alternate leaves are included in the Abietineae, and, almost without exception, 

 they also possess inverted ovules. 



FIG. 588. Juniperus Sabina: branch with fruit. Poisoxous. (After H. SCHENCK.) 



Sub-family Cupressineae. Some of the Cupressineae have needle-shaped leaves 

 in whorls (Juniper, Fig. 587) ; others have decussately-arranged, scale-like leaves 

 (Thuja, Juniperus sabina, Fig. 588). The former type is to be regarded as the 

 more primitive, for the seedlings of Thuja have needle-shaped leaves, and individual 

 branches of scale-leaved forms of Juniperus revert to the needle-shaped leaves in 

 whorls of three. The short shoots of Taxodium distichum have two ranks of leaves 

 and are shed as a whole. 



The Cupressineae, with the exception of Juniperus, are monoecious. The male 

 flowers of Juniperus communis stand in the leaf axils. At their base are a number 

 of small scale leaves (Fig. 587 A, a}, above which come several whorls of peltate 

 sporophylls (c) bearing 2-4 microsporangia (d) on the lower surface. The sporangia 

 open by a vertical slit parallel to the long axis of the sporophyll. The female 

 flowers occupy a corresponding position. The scale leaves at the base (Fig. 587 B] 

 are succeeded by a whorl of carpels (C, 6), each of which bears a single upright ovule 



