This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
(Greek, eu, well; kalypto, to cover as with a lid: the petals and usually also the calyx-limb fused and covering the flower before anthesis, then falling off in the form of a lid, or cover). Myrtaceae. Gum-Tree. Plate XXXIX. Mostly trees, frequently of immense size, a few of the alpine and sub-alpine species shrubby, much grown in California and the Southwest for their ornamental value, as windbreaks and avenue trees, for fuel, and especially for their timber.
Leaves simple, entire; in the seedlings and on young shoots of many species horizontal, opposite, sessile, and cordate; in the adult mostly vertical, alternate, petiolate (rarely opposite and sessile), and varying from roundish to lanceolate-acuminate and falcate; always rigid, penniveined, glabrous except rarely on the young shoots, sometimes covered with a glaucous wax: flowers white, rarely yellowish or some shade of red, in umbels of 3 to many, rarely solitary, the umbels solitary and axillary or paniculate or corymbose; calyx-tube obconical, campanulate, ovoid, or oblong, adnate to the ovary at the base; petals and calyx-lobes connate, forming a lid, or cap, which separates from the calyx-tube by a circumscissile dehiscence; lid sometimes plainly double, the outer cap then derived from the calyx-limb, the inner cap from the petals; stamens numerous; anthers small; style undivided: fruit a caps, partially or wholly inclosed in the adherent calyx-tube, opening at the top by 3-6 valves; seeds numerous, small, mostly angular. - About 300 species, all native of Austral, and the Malayan region.
Related to Ango-phora and to Syncarpia, but distinguished by the absence of distinct petals.
The genus Eucalyptus was monographed in part by Baron von Mueller in his Eucalyptographia (cited here as F. v. M. Eucal.), in which 100 species are illustrated (1879-84). The genus is now receiving exhaustive treatment by J. H. Maiden in his "Critical Revision of the Genus Eucalyptus," appearing in parts, with numerous plates. This author also furnishes the best information regarding the uses and timber of the various species, in his "Native Useful Plants of Australia." Bentham described 135 species in his "Flora Australiensis," vol. 3 (1866). The Australasian Association for the Advancement of Science published a very useful key by J. G. Luehmann in 1898. The most exhaustive American work on the genus is United States Forestry Bulletin No. 35, "Eucalypts Cultivated in the United States," by A. J. McClatchie. University of California Agricultural Experiment
Station Bulletin No. 196, by Norman D. Ingham, is a practical guide for planters, with descriptions of the more important species. The United States Forest Service, the California Station, and the California State Board of Forestry have all issued smaller bulletins on this subject. Inflated claims have been made for eucalyptus culture, and authentic publications should be secured if one contemplates planting them extensively.
Eucalyptus is a group adapted to semi-tropical and warm temperate regions. But few species are really hardy. E. globulus has been very widely distributed over the globe through the persevering efforts of the late Baron von Mueller; it is frequently planted in the malarial regions of warm climates, as at the Campagna at Rome, with very beneficial effect. (Sanitarians will be interested in "Eucalyptus in Algeria and Tunisia, from an Hygienic and Climatological Point of View," by Edward Pepper, Proc. Amer. Phil. Soc. 35:39-56.) In England, the same species is grown extensively for subtropical gardening, on account of its distinctive glaucous hue and symmetrical growth, but in that climate it needs the protection of glass in winter.
This is by far the most important genus of timber trees introduced into California. The ordinary blue-gum, E. globulus, has been grown in large numbers and is still the favorite for general planting. Its hard and durable wood is replacing oak and hickory to some extent for insulator pins, wheel-wrights' work, flooring, tool-handles, and furniture. Although pale in color, it takes a good polish, possesses a beautiful grain, and is readily stained. Furniture made from blue-gum wood and properly stained has every appearance of mahogany. The chief drawback to the use of eucalyptus for lumber is the tendency of its logs to end-check while curing, thus involving considerable waste. As a windbreak and fuel tree it is unsurpassed, since it is of rapid, erect growth and the timber is easily split. Its foliage has been distilled in large quantities for the oil it contains, practically all of the eucalyptus oil now sold in the United States coming from home-grown trees.
In addition to the blue-gum, E. rostrata and especially E. tereticornis are grown for railroad ties, piling, interior finish and furniture. E. resinifera is a hardy eucalypt yielding a good timber not so liable to check as that of some others; it has been but little grown in America thus far. E. corynocalyx is a good drought-resistant species for districts with mild winters, and its wood is of the best. E. crebra will grow under a greater range of conditions than perhaps any other and is especially suited to the hot and dry interior valleys. Other drought-resistant eucalypts are E. microtheca and E. polyanthemos, while the most resistant to frost are E. crebra, E. rostrata, E. tereticornis, E. globulus, E. viminalis, E. rudis, E. robusta, and E. resinifera. The species most cultivated as ornamentals are E. ficifolia, E. leucoxylon, E. sideroxylon variety rosea, E. Risdonii, E. erythronema and E. polyanthemos. Persistently repeated accounts of heights ranging from 325 to 500 feet for certain eucalypts are erroneous, as indicated under E. amygdalina variety regnans.
Although the eucalypti are not exclusively, and some species not even prominently horticultural, yet because of the great general interest attached to them and because of their varied uses, it is thought best to discuss them rather fully in this Cyclopedia.