This section is from the book "The Gardener's Monthly And Horticulturist V26", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
These trees have been found to grow very well in many parts of California. Prof. Hilyard has been experimenting with them on the University grounds at Berkely, and writes that the wattles, Nos. 1, 2 and 3, are species of Acacia used in Australia as sources of tan-bark, which is known in commerce as "mimosa bark." All are more or less in cultivation in California for ornamental purposes - the tine most commonly seen being No. 2, with feathery leaves and golden-hued, odorous flowers, now just bursting into bloom. It is usually designated by nurserymen as Acacia molissima, which name, however, according to Von Muller, properly belongs to the black wattle, No. 1, while No. 2 should be known as Acacia dealbata, from the whitish silvery sheen of its leaves. Both are supposed to be mere varieties of one and the same species - Acacia decurrens. It will be noted, however, that they differ very widely in value as sources of tan-bark, the silver wattle only showing half the amount of tannin contained in the bark of the black variety.
But even this does not fully express the superior value of the latter, the bark of which is nearly one-quarter of an inch in thickness, while that of the former is less than half as thick, viz., three-thirty-seconds of an inch, so that in one case the cost of production would be bestowed upon less than one-fourth of the active tannin produced in the other. As the two kinds are very much alike in appearance, it is important to bear this fact in mind. The plants now offered for distribution from the University are seedlings grown from a tree on the grounds of the institution, thirteen years old, which is twelve inches in diameter three feet above the ground and forty feet high - therefore, of rapid growth. The wood is used for cask staves, wagon-making, etc., in Australia, and is excellent firewood.
No. 3 - the golden wattle - though having a bark ' equal in every respect to the black wattle, is a much smaller tree; hence more costly in stripping and the wood of less value.
All are quite modest in their requirements as to soil and care.
Further details on this subject may be found in the report of the College of Agriculture for 1882, and in the United States Agricultural Report for 1878.