103 



A second memoir of MM. Bravais* treats of the symme- 

 trical arrangement of inflorescences ; a work which is still more 

 comprehensive than the first. On account of limited space 

 I am merely able to communicate the summary which the 

 authors have given at the end of the various paragraphs, be- 

 lieving that in this manner the results which they think they 

 are able to draw from their laborious researches, will most pro- 

 minently appear. 



With reference to the inquiries respecting the uninodal cyme 

 of Monocotyledons, we find the following summary. 



1. The uninodal cyme is the type of the cymes presented 

 by monocotyledonous plants. 



2. The pedicel of each flower is furnished with a single 

 bract, susceptible of abortion, whence a second pedicel does 

 or may originate. 



3. This bract indicates the spiral order of the pedicel. 



4. The cyme may be helicoid, scorpioid or distichous, ac- 

 cording to whether the pedicels are homodromous or antidro- 

 mous or distichous. 



5. It may be prolonged or contracted according to the 

 state of the pseudothallus, with sessile or pedicellate, simple 

 or double flowers ; this last case happens when it is dichoto- 

 mous at its origin. 



6. It may be terminal or axillary, and in this second case 

 the inflorescence is generally a thyrsus ; as yet however we 

 have not met with a terminal cyme among the scorpioids. 



7. The double helicoid cymes have their two halves homo- 

 dromous. 



8. The double scorpioid cymes appear on the contrary to 

 have their first pedicels antidromous to one another. 



The following results have been taken from the paragraphs 

 on the bracts of dicotyledonous inflorescences. 



1. The greater number of dicotyledonous flowers have 

 their pedicel furnished with two lateral bracts, sometimes de- 

 veloped, sometimes more or less entirely abortive. 



2. These two bracts are most frequently the first leaves of 

 a spiral proceeding from the primitive leaf and in continua- 

 tion with the sepals ; and when they are inserted at equal 



* Essai sur la disposition symmetrique des inflorescences. Ann. des 

 Scienc. Nat. 1837, pp. 193, 291, 348, and vol. ii. p. 1142. 



