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PRINCIPLES OF PLANT-TERATOLOGY. 



Annual herbaceous plants, under ordinary condi- 

 tions branched, may through malnutrition develop no 

 branches at all. 



Klein describes a remarkable instance of this phe- 

 nomenon in the allspice (Galycanthus) and marigold 

 (Calendula), where, an axillary shoot being completely 

 suppressed, its first pair of leaves became laterally 

 con crescent, thus affording an instance of one leaf being 

 axillary to another leaf (of. ovuliferous scale in Coni- 

 fers). 



Fusion. 



The union of two or more shoots may be either post- 

 genital or congenital, as has been already explained in 

 a previous section. It may occur between shoots of the 

 same morphological nature or between those of different 

 nature ; between main shoots or between a main shoot 

 and its axillary branch. There may be no external 

 sign of fusion, or there may be more or less pronounced 

 sutures present, indicating to the observant the lines 

 of fusion between the two shoots. 



1. Postgenital.- — Well-known instances of this are 

 the H-formations in large trees due to the intimate 

 cohesion of the tips of two branches growing in oppo- 

 site directions towards each other ; here the fused 

 organs belong to quite distinct individuals. An ex- 

 cellent instance of this was observed in the case of 

 Eucalyptus salmonophloia : two cross-bars occurred, one 

 close above the other; a very rare case. The "Arbre 

 aux cent chevaux " on Mount Etna is a chestnut, 52 

 metres in circumference, the thickness being the result 

 of the fusion of several trunks growing from the same 

 root. Legrand saw in the Ardennes an oak which was 

 formed by the fusion together of four trunks which 

 became free again above ; the oak bears the name 

 of "Arbre des quatre fils d'Aymon." Moqum-Tandon 

 observed two shoots of asparagus which were free and 

 distinct at the base, in contact about the middle, and 



