xxviii BOTANT. 



the bract B, which is always on the anterior side, while the axis is 

 always posterior. 



Symmetrical Flowers.— "When all the members on each whorl 

 are equally developed, having the same size end form, the flower 

 may be vertically bisected in any plane into two equal and similar 

 halves; it is then actinomorphie (= regular and polysymmetrical, 

 Fig. XXII). When the members in each whorl are unlike in size 

 and form, and the flower is capable of bisection in only one 

 plane, it is zijgomorphie (= irregular and monosymxnetrical. Fig. 

 XXIII). In the latter there is generally more or less of an abor- 

 tion of certain parts; i.e., one or more of the sepals, petals, 

 stamens, or pistils are but partially developed, appearing in the 

 flower as rudiments only. Sometimes this is so marked as to re- 

 sult in tlie complete suppression of certain parts. 



Suppression of Parts. — It not infrequently happens in both 

 actinomorphie and zygomorphic flowers that entire whorls are 

 suppressed; this gives rise to a number of terms, as follows: 



When all the whorls are present (not necessarily, however, aU 

 menibers of all the whorls) the flower is said to be complete; when 

 one or more of the whorls are suppressed, the flower is incomplete. 

 As to its perianth, the flower is said to be 

 Diehlamydeous, wlien both the whorls of the perianth are pres- 

 ent; 



Monoehlamydeous, when but one (usually the calyx) is present ; 

 Apetalous, when the corolla is wanting; 

 ' Aehlamydeous, or naked, when both calyx and corolla are 



wanting. 

 As to its sexual organs, the flower is 

 Bisexual {ov'hermaphrodite),w'hon stamens and pistils are present; 

 Unisexual, when, of the essential organs, only the stamens are 

 present (then staminate), or only the pistils (then pistillate ; 

 Neutral, when both stamens and pistils are wanting. 

 Collectively, bisexual flowers are said to be monoclinous; uni- 

 sexual flowers, diclinous ; while in those cases where some flowers 

 are bis3xual and others unisexual they are, as a whole, said to be 

 polygamous. 



Biclinous flowers are further distinguished into 



Monceaious, when the staminate and pistillate flowers occur on 



■the same plant, and 

 Dioecious, when they occur on different plants. 



