132 FLORA OF TASMANIA. \}IyrtacecB. 
look very different from one another. To study the " Gum-trees" well, it is further necessary to study the other 
plants of the Colony, for the results of an observer's experience in such a genus will be entitled to more or less 
weight very much according to the amount of knowledge he possesses of the limits of variation, etc., in other 
plants: in short, it requires an experienced and very cautious oWner to monograph the Australian Gum-trees, 
for it is no doubt one of the most difficult tasks in all systematic botany, and at the same time one of the most 
atific point of view. 
Of the economic value of the Gum-tree timbers I regret to say that I have little definite information, owing to 
the difficulty of ascertaining the precise species upon which observations have been made and published. In the 
Proceedings of the Eoyal Society of Tasmania I find some veiy valuable notices by Messrs. Milligan, Mitchell, 
Watson, Hull, and Ewing, respecting the Blue Gum, Swamp Gum, Stringy Bark, Peppermint Gum, Myrtle-leaved 
Gum, Ash Gum, Iron-wood, Mountain Gum, Weeping Gum, Black-but Gum, and White Gum. Of these the Blue 
Gum is no doubt E. Globulus, a rapid-growing tree, with excellent wood, attaining a gigantic size both in Southern 
Australia and Tasmania. The Swamp Gum and Stringy Bark are perhaps both referable to my E. gigantea, under 
which two species may be confounded by me, or the Swamp Gum may be some other species attaining a gigantic 
size in damp hollows. Mr. Mitchell describes the Swamp Gum as so very like the E. Globulus as not to be easily 
distinguished, but with smaller leaves and thinner bark, as being the largest of the genus, and growing twice as fast 
as E. Globulus ; he mentions trees 251 feet to the first branch. The Stringy Bark he distinguishes by its much 
thicker, fibrous bark ; Mr. W q a note that this Stringy Bark is the most gigantic of all, that 
it is well named gigantea by me, and that he has measured a sound trunk 64 feet in girth at 4 feet above the 
ground, and 200 feet high to where it was broken off, and containing 200 tons of timber. Mr. Watson adds that 
the wood of E. Globulus is equal to English Oak in density, and superior on account of the great length attainable, 
whereas the Stringy Bark is not approved for shipbuilding, because it shrinks and swells with variations of humidity. 
Mr. Hull mentions a hollow E. Globulus at Tolosa as 84 feet in circumference at the ground, and 78 at 6 feet 
above the ground, its estimated height being 330 feet. Lastly, the Eev. Mr. Ewing gives details of a Swamp 
Gum-tree, also hollow, found near Hobarton, which was 130 feet in circumference at the ground, and 102 at 3 
I have preferred giving these data here to placing them under the supposed species to which they refer, and 
would earnestly recommend that in all cases of observations or experiments being made on these and other trees, 
specimens of leaves and flowers and fruit be dried between papers, accurately ticketed, and deposited in the Museum 
of the Society at Hobarton, and, if supposed to be unknown or undescribed, figured in the Eoyal Society's Pro- 
ceedings. 
The genus Eucalyptus is at once recognized by its cup-shaped calyx of various forms, crowned with a deciduous 
operculum (which assumes also many forms), and which consists of the combined calyx and corolla. A fringe of 
free stamens crowns the mouth of the calyx, and the fruit is a three- to five-celled woody capsule, bursting by 
short valves usually within the mouth of the calyx, and containing numerous small seeds. The leaves are inva- 
riably opposite in the young plant, but are veiy rarely so in the old one; when alternate, their surfaces are mostlv 
quite similar, and the petiole is half twisted, so that the plane of the leaf is parallel to the axis of the tree. (Name 
from rv, well, and KaAvm-w, to cover ; in allusion to the operculum.) 
§ 1. Leaves opposite at all periods of growth. 
1. Eucalyptus cordata (Lab. Nov. Holl. ii. 13. t. 152); foliis glaucis plerisque oppositis ses- 
siiibus late cordatis crenulatis, ramulis teretibus novellis tetragonis, floribus 3-4 pedunculo brevissimo 
sessilibus, operculo depresso cupula subglobosa breviore.— Be Cand. Prodr. iii. 221, {Gunn, 1071.) 
Hab. Recherche Bay -and Iluon River, Lalillardiere, Gunn.—(Fl Oct.) (Cultivated in England.) 
A small tree, very confined in its locality, easily recognized by its sessile, opposite, broadly cordate, blunt or 
apieulale, crenate leaves, -that are bilobed at the base.— Flowers generally in threes, almori wawile. Calyx obconic 
when young, almost globose in fruit. Operculum short and broad. 
