THE FLOWER ^ 15 



en masse, or two cycles (especially petaliferous and staminifer- 

 ous) having a common origin (Fig. 1, C, D). Goebel holds (Or- 

 ganographie) that at least in some epigynous flowers (as Pirns 

 Mains) the carpels do not merely roof the ovular cavity but also 

 line it, basing the claim upon a study of the meristematic tissue ; 

 in which case the wall of the so-called " ovary " is toral without 

 and carpellate within. It is to be expected that numerous in- 

 termediate stages between complete hypogyny and extreme 

 epigyny will be displayed, as may be inferred even from the 

 doubtful phrases employed by taxonomists to describe them. 

 It also seems to be a safe conclusion, since epigyny is con- 

 stantly associated with the most specialized groups of each great 

 division, as Orchidaceae among Monocotyledons, Umbelliferae 

 among Archichlamydeae, and Compositae among Sympetalae, 

 that it is a mark of higher rank than hypogyny in any evolu- 

 tionary series. 



The tendency for the members of a floral set to develop 

 unequally, resulting in zygomorphy or various forms of " irreg- 

 ularity," is not general, and can not be applied so broadly as 

 can the tendency to the cyclic arrangement or to epigyny. In 

 certain groups, however, it is very pronounced as a special 

 character, as Orchidaceae among Monocotyledons, Legumi- 

 nosae among Archichlamydeae, and Personales among Sympet- 

 alae. The occurrence of zygomorphy in relatively primitive 

 as well as in highly specialized groups indicates that it is to be 

 regarded as a special rather than a general tendency; and yet, 

 other things being equal, the zygomorphic flower is to be re- 

 garded as of higher rank in any given evolutionary series than 

 the actinomorphic flower. Diversities resulting from inequali- 

 ties of growth are often described in terms of symmetry, a 

 term that unfortunately has two applications in connection 

 with the flower, for its well-known biological use by Sachs 

 found it already used to designate a flower " in which the mem- 

 bers of all the cycles are of the same number." In its biological 

 sense a symmetrical flower is one " that can be divided into 

 two similar halves, or the parts of which are radially disposed 

 around a central point." The terms " monosymmetrical " and 

 " poly symmetrical " are logical, but not better than the older 

 terms of Eichler, " zygomorphic " and " actinomorphic." How- 

 ever, the phenomena of floral symmetry are not well expressed 



