GLOSSOLOGY OF ANGIOSPERMS. 431 



are unlike in size and form, and the flower is capable of bisection in 

 only one plane, it is zygom-n phic (= irregular, and monosyminetrical). 

 In the latter there is generally more or less of an abortion of certain 

 parts i.e., one or more of the sepals, petals, stamens, or pistils are but 

 partially developed, appealing in the flower as rudiments only. Some- 

 times this is BO marked as to result in the complete suppression of cer- 

 tain parts. 



It not infrequently happens in both actinomorphic 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, all mem- 

 bers 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 



Dichlamydeous, when both the whorls of the perianth are present , 

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

 Apetalous, when the corolla is wanting ; 



Achlamyde^us, or naked, when both calyx and corolla are wanting ; 

 As to its sexual organs, the flower is 



Bisexual (or hermaphrodite) when stamens and pistils are present ; 

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

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

 Neutral, when both stamens and pistils are wanting ; 

 Collectively, bisexual flowers are said to be mon 1 clinous ; unisexual 

 flowers, diclinous ; while in those cases where some flowers are bisex- 

 ual and others unisexual they are, as a whole, said to be polygamous. 

 Diclinous flowers are further distinguished into 

 Mon&cious, when the staminate and pistillate flowers occur on the 



same plant, and 



Dmcious, when they occur on different plants. 



The Perianth. In a large number of flowers the parts of the 

 calyx and corolla (sepals and petals) are distinct i.e.. not at all united 

 to one another ; such are said to be chorisepaloun* as to the calyx, and 

 choripetalous as to the corolla. The terms polysepalous and polypttal- 

 i.us are the ones most commonly used in English and American books 

 on botany, although they manifestly ought to be used as numerical 

 terms. Eleutheropetalous f and dialypetalous \ are also somewhat used, 

 especially in German works. 

 The numerical terms usually employed are mono-,% di-, tri-, tttra-, 



* From Greek ^up/feiv, to sever, to separate. 



f From Greek efcvQepos, free. 



J From Greek Atahvetv, to part asunder. 



The terms moncsepalous and monopetalous were formerly used with 

 a different meaning from that given here ; they were applied to the 

 forms now called gamosepalous and gamopetalous. This use, errone- 



