Weeds are very numerous (about 125); and some, notably the sand-bur (Solanum rostratum) cockle-bur, and tumble-weeds among indigenous, and the Russian thistle (Salsola tragus) and purslane among non-indigenous species, are agricultural pests.
Among the clubs of the city are the Pacific Club, founded in 1853 as the British Club; the Scottish Thistle Club (1891), of which Robert Louis Stevenson was a member; the Hawaii Yacht Club, and the Polo, Country and University Clubs.
In the American button-bush the heads are globular, in some species of teazel elliptical, while in scabious and in composite plants, as sunflower, dandelion, thistle, centaury and marigold, they are somewhat hemispherical, with a flattened, slightly hollowed, or convex disk.
It is familiar in the titles, showing the colour of their wands of office, of the gentlemen ushers of the three principal British orders of knighthood, the ushers of the Garter and St Patrick being "Ushers of the Black Rod," and of the Thistle "Green Rod."
In some instances buds form on the roots, and may be used for purposes of propagation, as in the Japan quince, the globe thistle, the sea holly, some sea lavenders, Bocconia, Acanthus, &c. Of the tendency in buds to assume an independent existence gardeners avail themselves in the operations of striking " cuttings," and making " layers " and " pipings," as also in budding and grafting.