xxviii BOTANY. 
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 and form, the flower 
may be vertically bisected in any plane into two equal and similar 
halves; it is then actinomorphic (= 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 zygomorphie (= irregular and monosymmetrical, Fig. 
XXIII). In the latter there is generally more or less of an ador- 
tion of certain parts; ie, 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 the complete svppression of certain parts. 
Suppression of Parts.—It not infrequently happens in both 
actinomorphic and zygomorphie 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, all 
members of all the whorls) the flower is said to be complete; when 
one or more of the whorls are suppressed, the flower is cncomplete. 
As to its perianth, the flower is said to be 
Dichlamydeous, when both the whorls of the perianth are pres- 
ent; 
Monochlamydeous, when but one (usually the calyx) is present; 
Apetalous, when the corolla is wanting; 
Achlamydeous, or naked, when both calyx and corolla are 
wanting. 
As to its sexual organs, the flower is 
Bisexual (orhermaphrodite), when 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 bisoxual and others unisexual they are, as a whole, said to be 
polygamous, 
Diclinous flowers are further distinguished into 
Monecious, when the staminate and pistillate flowers occur on 
the same plant, and 
Diecious, when they occur on different plants. 
