1888. | BOTANICAL GAZETTE. 147 
mentali e meccaniche), the influencing or conditional (cause 
influenti o condizionali), the final, functional, or biological 
(cause finali, funzionali, o biologiche). 
zygomorphy four grades are distinguished. In the 
first grade (recentissima) the irregularity is limited toade- 
flection of the stamens and styles. The second (recente) and 7% 
the third (inveterata) form transitions to the fourth (invetera- 
tissima), in whi 
ich there is unequal development of one or 
more circles with partial or total abortions of certain organs, 
as in the orchids. Flowers of the first two grades belong to 
groups in which the types are regular, those of the last two 
rom the point of view of final or functional causes zygo- 
morphy is an adaptation for cross-fertilization by special in- 
sects and honey-sucking birds. Most irregular flowers are 
moths (sfingofili) and birds (ornitofili), 
flies. Ifthe stamens and styles turn s 
under surface of the visitor, the flower is sternotribe hip pollen ae 
1s applied to the side of the insect, the flower 1s pleurotribe. cee 
Nototribe flowers adapted to bees are most eee | 
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tobirdsis Epiphyllum truncatum.® Sternotribe bee-flowersare 
most Papilionacéze, Rhododendron, etc. Amaryllis formo- —— 
Sissima is adapted to birds,’ and Lilium longiflorum 1s sphing- | aa 
ophilous. Pleurotribe flowers are adapted to bees, € S+ 
_ Stamens turn down and the styles turn up; in Ocymum ss ve 
stamens turn up and the style turns down. In the female st 
age i 
MBs These adaptive movements are referred to the operation 
o biological causes. Wind-fertilized flowers are actinomor- 
Phic, and belong to actinomorphic orders. : : 
© the mechanical theory of De Candolle, that irregu- 
*** Potendo darsi : Bea ed iba cive,sternotriba e pleurotriba.” i 
= i tre sorta d’impollinazioni, nototriba cioe,ster “Trelease Am. _ 
Nat. xing . ae and Salvia splendens are other examples. See Trel 
Tre, 227, and XV. 265, bine 
lum _majus is commonly visited by the ruby-throated hummin Jassia 
Chamaret aps better examples were described by J. E. Todd, Am. Nat. XVI. 281, CAs 
“crista and Solanum rostratum. 
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