150 BOTANY. 



(6.) It is very common for the young leaves to appear in 

 succession on the punctum vegetationis at a distance equal 

 to two fifths of the circumference from each, producing a 

 five-ranked arrangement. 



(7. ) A seven-ranked arrangement is rarely seen ; it is pro- 

 duced by the leaves following each other at a distance of two 

 sevenths of the circumference. 



(8. ) An eigM-ranked arrangement, which is a very common 

 one, results from the leaves appearing at the constant distance 

 of three eighths of the circumference. 



(9.) In like manner there may be formed 9, 11, 13, 14, 18, 

 21, 23, 39, 34, 37, 47, 55, and 144 ranks. 



198. — The distance between any two succeeding leaves is 

 called the angular divergence; it may generally (but not always) 

 be deduced directly from the number of ranks (orthostichies); 

 thus in the 2-ranked leaves it is \ ; in the 3-ranked, \; in 4- 

 ranked, \ ; in 5-ranked, f (rarely -^) ; in 7-ranked, f ; in 8- 

 ranked, f- (rarely ^) ; in 9-ranked, f ; in 11-ranked, -^ ; in 

 13-ranked, ^ ; in 14-ranked, ^ ; in 18-ranked, -f^ ; in 21- 

 ranked, ^ ; in 23-ranked, ^-j ; in 29-ranked, -^ ; in 34- 

 ranked, -^ ; in 37-ranked, -j\ ; in 47-ranked, Jf ; in 55- 

 ranked, f^ ; in 144-ranked, -f^^. 



Examples of the more common of these arrangements are to be 

 found as follows .* 



(ffi.) 3-ranked in Fagus, Oeliis, TJVmus, Vitis, Tilia, most .FicJeos, and 

 all grasses. 



(6.) 3-ranked in Carex, Scirpus, and most Jungermanniai. 



(c). 4-ranked in the bracts of the principal axis of inflorescence of 

 Jtestio erectus and ThamnocJiortus scariosus. 



(d.) 5-ranked in Quercus, Populus, Robinia, most Jtosacete, Borra- 

 igivacecB, etc. ; this is the most common arrangement in Dicotyledons. 



(«.) 7-ranked in Melaleuca ericcsfolia. Euphorbia hepiagona, Sedum 

 aexangvlare, etc. 



(/.) 8-ranked in Polytriclmm,'Parietaria erecta, Antirrhinum ma- 

 jus, Baplianus. Brassica, Hieracium pilosella, etc. 



,(g ) 9-ranked in Lycopodiwm selago. 



i(/i.) 11-ranked not rarely in Sedum reflexum and Opuntia vulgaris. 



(k.) 13-ranked in Verbascum, Rhus typhina, Tsuga canadensis. 



* This list of examples is from Hofmelster's " Allgemeine Morphol- 

 lOgie der Qewaohse," p. 448 et seq. 



