ANGIOSPERMS. 



539 



it continues to develope, the part common to the whole whorl of floral leaves. 

 The coherent tubular or campanulate part does not therefore consist of originally 

 free portions which cohere subsequently by their edges, but from the very first it 

 forms a whole which is intruded, so to speak, at the base of the perianth-leaves ; 

 the originally free leaves eventually forming the marginal teeth of the common 

 basal portion. Applying the term Sepal to a calycine, Petal to a corolline leaf, 

 a calyx consisting of coherent leaves is gamosepalous or synsepalous, a corolla con- 

 sisting of coherent leaves gamopelalous or sympetalous ; if the leaves of the perianth- 

 whorl are not coherent, but free, this is expressed by the terms eleutherosepalous 

 or aposepalous, and eleutheropetalous or apopetalous^. When there is only one 

 perianth-whorl, and it is desired to state whether it consists of coherent or of free 

 leaves, the terms gamophyllous or symphyllous and eleutherophyllous or apophyllous 

 may be used. It sometimes happens moreover that two perianth-whorls coalesce 

 into one, so that, for example, two alternating trimerous whorls have united into a 

 six-toothed tube (as in Hyactnthus, Muscari, &c.). 



Fig. 361. — Longitudinal section through the flower oi Lychnis flos-Jovis ; y the elongated portion of the axis 

 (anthophore) between calyx and corolla ; x ligule of the petals or corona. 



If the leaves of the outer and inner whorls are free (not coherent), and if 

 the distinction between calyx and corolla is clearly marked, then, in addition to 

 the structural distinctions already named, other differences of form are also usually 

 to be observed. The sepals have generally a broader base, are sessile, usually of 

 very simple outline and pointed at the apex ; the petals have mostly a narrower 

 base, their upper portion is often very broad, and a distinction is not unfrequently 

 apparent of claw {unguis) and blade {lamina), and the lamina is often divided or 

 otherwise segmented. At the point where the lamina bends back from the unguis, 

 ligular structures are often formed on the inner or upper side, which, when treating 

 the flower as a whole, are comprised under the term Corona, as in Lychnis 

 (Fig. 361), Saponaria, Nerium, Hydrophylleae, &c. When the corolla itself is 



^ The terms ' polysepalous ' and ' polypetalous ' are objectionable, since these terras do not 

 express the contrast correctly ; still more so are ' monosepalous ' and ' monopetalous,' as applied to 

 the coherent whorls, because they have no reference to the true nature of the phenomenon. 



