24 ON THE PH-±:^OGAMIC VEGETATION OF RODKIGL'EZ. 



to breadth of lamina being vastly different in the juvenile form 

 from what it is in the adult. The lamina is entire, developing 

 equally, though toothings characteristic of the adult may be seen ; 

 but it is never lobed or cleft. The leaves in the young plant are 

 thus more or less linear or lanceolate, and, as a rule, greatly exceed 

 the adult in length, being sometimes twice or thrice as long. This 

 is the commonest Itind of variation, occurring in nine species, viz. 

 Dombeyaferruijinea^ El<Jeod€ndron orientalej Terminalia JBemoin, 

 Foetidia mauritiana^ Mathurina penduliflora^ Handia heterophylla, 

 Pyrostria trilocularts, SeypTioclilamys revoluta^ and Diospyros diver- 

 sifolia. Only in Pyrostria trilocularis and Diospyros diversifoHa 

 the linear juvenile leaves do not greatly exceed the adult in length. 

 Probably JEugenia cotinifoUa is also heterophyllous after this 

 type. 



In four species the third type of heteromorphism is seen. Here 

 the lamina in the leaves of the young plants develops unequally, 

 and thus a lobed or cleft leaf is formed ; but the relative propor- 

 tion of length to breadth of lamina is the same in both juvenile and 

 adult. The amount of lobation in the juvenile leaves varies ; they 

 may be even twice or thrice cleft ; and according as the leaf is 

 pinnately or radiately veined, the leaf is pinnatifid, or palmatifid. 

 The species in which this type is seen are Aphloia mauritiana, 

 Hibiscus liliijlorus yQuivisia laciniafa^^nA Clerodendron laciniaiunt* 

 In Hibiscus liliijlorus the palmatifid form occurs ; the other three 

 are pinnatifid. In Abrotanella rJiyncocarpa^ a small Composite 

 herb, the leaves as they get older tend to become pinnatifid, the 

 young being quite entire. Its variation, then, is the converse of 



this third type. 



In addition to the alteration in form, there is often a difference 

 between the habit and consistence of the leaves in the juvenile 

 and adult plants. Dombeya ferruginea shows this very well. Its 

 green glabrous juvenile leaves are, in the adult, clothed on the 

 under surface with a dense brown tomentum. The converse is 

 sometimes seen, for instance in Mandia heterophylla, where pu- 

 bescent juvenile leaves become glabrous in the adult. As to 

 consistence, the hard rigid young leaves of Ludia sessilijlora and 

 Carissa Xylopicron become in the male more flaccid and coria- 

 ceous. 



It is curious that Hibiscus {Paritiuni) liliaceus is not hetero- 

 phyllous In Kodriguez, though it is recorded as being so on the 



