604 PHANEROGAMS. 



investigate these relationships for himself must observe that the long inferior ovary of 

 most Orchids undergoes a torsion {resupination) at the time of the opening of the flower, 

 which causes the posterior side of the flower to assume an anterior position ; but trans- 

 verse sections even of advanced buds show clearly the true position of the parts of the 

 flower in relation to their mother-axis. 



The flowers of most Monocotyledons, like those of Orchids and Grasses, can be de- 

 rived from a type which is actually seen in Liliaceae, and which represents a flower 

 consisting of five alternating whorls, each with three members, of which the two outer 

 ones constitute the perianth, the two next the androecium, and the last the gynaeceum ; 

 although the latter may sometimes be represented by two whorls. Occasionally instead 

 of abortion an increase of number takes place in particular whorls, by the formation 

 of one member instead of two (as in Butomus, Fig. 382). 



Increase in the typical number of the members of a whorl may arise in different 

 ways, as the following examples will show. According to the detailed researches of 



Fig. 411. — Diagram of the flower of Fumariacerc (after Eichlcr). 



Eichler^, the flowers of Fumariaceae may be referred to a type in which there are six 

 decussate pairs of members (Fig. 411), viz. 



two median sepals, 



two lower lateral (exterior) petals, 



two upper median (interior) petals, 



two lateral stamens, 



two median (always abortive) stamens, 



two lateral carpels. 



The two lateral stamens are however represented in some genera (as Dicentra and 

 Corydalis) by-two groups, each consisting of three stamens, an inner one with an entire 

 quadrilocular anther, and two lateral stamens each with a bilocular anther, a struc- 

 ture which Eichler explains on the hypothesis that the lateral stamens are only stipular 

 structures, and therefore branches from the base of the middle one. In Hypecoum 

 Eichler assumes a cohesion of each pair of opposite stipular stamens so as to form an 

 apparent whorl of four stamens. 



Eichler also deduces the flowers of Cruciferse and Cleomeae (a section of Gappa- 

 rideae) from a type represented by Fig. 412 ^, which is also the empirical diagram for 

 Cleome drosercpfolia, and for certain species of Lepidium, Senebiera, and Capsella, This 

 typical flower consists of 



two lower median sepals, 



two upper lateral sepals, 



four diagonal petals in one whorl, 



two lower lateral stamens, 



two upper median stamens, 



two lateral carpels. 



^ Eichler, Ueber den Bliithenbau der Fumariaceen, Cruciferen, und einiger Capparideen, in 

 (Regensburg) Flora, 1865, nos. 28-35, and 1869, p. i. — Peyritsch, Ueber Bildungsabweichungen der 

 Cruciferenbluthen, Jahrb. fur wiss. Bot. vol. VIII. p. 117. 



