CHARACTERISTICS OF THE GENUS EUCALYPTUS. 



The Eucalyptus derives its name from two Greek words which may be trans- 

 lated as "well-covered" — a name applied to the little cap which protects the 

 unopened flower, and one which aptly describes what is perhaps the leading feature 

 of the genus. The most noticeable feature about a Eucalyptus flower is the absence 

 of both sepals and petals, and the presence of the operculum or bud-cap which pro- 

 tects the stamens in the bud stage. The operculum usually falls off entirely as 

 the flower expands, but sometimes remains hinged on to the calyx after the flower 

 opens. These characteristics, together with the presence of the inferior ovary 

 and the conspicuous stamens of indefinite number, serve to distinguish the genus 

 Eucalyptus from all other flowering plants. The Eucalypts are closely allied to 

 the genus Angophora, which is found only in the Eastern States, and in which 

 there are petals which soon fall after expansion, and small but distinct calyx- 

 teeth. The calyx of Eucalyptus, although generally without lobes or teeth at all, 

 has, in a few instances, small teeth, four in number, which are situated at or near 

 the top of the calyx, and which appear to be the rudiments of sepals. The 

 operculum of Eucalyptus takes the place of petals as regards their protective 

 functions, but the filaments are the most conspicuous part of the flower, and, being 

 attractive, serve as petals in this respect. If, as is generally supposed, the 

 Angophoras are the ancestors of the Eucalypts, the operculum may have, at one 

 time, consisted of free petals. In some species of Eucalyptus the operculum is 

 double— the outer one falling off before the inner. 



The Eucalypts are all evergreen trees or shrubs, with the exception of one 

 tropical tree which is deciduous, and another from the same latitude which is 

 partially deciduous. Eucalypts have simple leaves which usually have leaf 

 stalks. The leaves are generally of a lance or egg shape. The venation consists 

 of a midrib connected by fine secondary veins with a vein which runs close to 

 the margin of the leaf (intramarginal). With few exceptions, the bracts and 

 bracteoles so characteristic of other flowering shrubs and trees are absent from 

 Eucalyptus, and, when present, are either rudimentary or fall before the flower- 

 ing period. 



Eucalypts are divided, as regards their habit, into Trees, Shrubs, Mallees and 

 Marlocks. Trees are distinctive in habit, in that, they possess a well defined 

 trunk. Shrubs branch from the base, or close to the base. Mallees have a 

 bulbous root-stock, either subterranean or half above the soil, from which arise 

 stems (usually 4 to 8 in number), which are all of about the same height. 

 Typical Mallees have a large woody stock. Marlocks, which may be called 

 "sand-plain Mallees," have a smaller reduced stock, or become true shrubs. 

 It is often difficult to differentiate between a Marlock and a shrub, as inter- 

 mediate forms occur, which may be one or the other. Trees and Mallees, on the 

 other hand, are quite distinctive forms of vegetation. For the sake of conveni- 

 ence, the Mallees, Marlocks and true shrubs, have been placed in the same 

 general key. 



