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, like a hedgehog; alluding to the spiny involucral scales). Composite. Globe Thistle. Coarse thistle-like plants, with blue or whitish flowers in globose masses, sometimes used in the wild garden.
More or less white-woolly herbs: leaves alternate, sometimes entire, usually pinnate-dentate or twice or thrice pinnatisect, the lobes and teeth prickly: flowers in globes; the structure of one of the globes is very odd; each flower in the globe has a little involucre of its own, and the whole globe has one all-embracing involucre; flowers perfect and fertile (or sterile by abortion), corolla regular and no ray-flowers; pappus of many short scales forming a crown: achene elongate, 4-angled or nearly terete, usually villous. - About 60 species, from Spain and Portugal to India and Abyssinia.
Globe thistles are coarse-growing plants of the easiest culture, and are suitable for naturalizing in wild gardens and shrubberies. An English gardener with an eye for the picturesque (W. Goldring) recommends massing them against a background of Bocconia cor-data, or with such boldly contrasting yellow- or white-flowered plants as Helianthus rigidum or Helianthus multiflorus. The best species is E. ruthenicus (form of E. Ritro). A few scattered individuals of each species are not so effective as a condensed group of one kind.
E. ruthenicus flowers in midsummer and for several weeks thereafter. The silvery white stems and handsomely cut prickly foliage of globe thistles are interesting features. They make excellent companions for the blue-stemmed eryngiums. All these plants are attractive to bees, especially E. exaltatus, which has considerable fame as a bee-plant. Globe thistles are sometimes used abroad for perpetual or dry bouquets.
A. Leaves not pubescent nor setulose above but sometimes roughish above.
Tall thistle-like plant, with pinnate-lobed leaves, which (like the stems) are tomentose beneath, the lobes lanceolate or linear and cut, but not spiny: involucre scales setiform, the inner ones much shorter: flowers blue, very variable. G.M. 46:69. R.H. 1890, p. 524. G. 31:611. variety tenui-folius, DC. (E. ruthenicus, Hort.), has the lower leaves more narrowly cut, more or less spine-tipped. Gn. 45:174. - Perennials of S. Eu., growing 2-3 ft. high. They bloom all summer. Leaves sometimes loosely webby above.
Tournefortii, Ledeb. (E. Tournefourtiana, Hort.). Three to 4 ft., the stems branched and velvety: leaves rough above, white-hairy below, much divided into 5 linear segments, spiny: heads "silver-gray" (bluish), the involucral bracts free, bristly. E. Medit. region. Sept, B.M. 8217. R.H. 1906, p. 523. - Suitable for dry places.
aa. Leaves pubescent or setulose above.
b. Plant perennial.
Linn. Tall (5-7 ft.): leaves pinnatifid, viscose-pubescent above, tomentose below, the teeth of the broad lobes yellow-spined: flowers white or bluish, the involucral bracts subulate-acuminate, free. S. Eu. B.R. 356 (as E. panic-ulatus).
Bieb. Three to 4 ft.: leaves very hairy on both surfaces, webby above, those of the stem essentially entire, the radical leaves sinuate-lyrate, almost unarmed; stem - leaves with spiny tips: heads large, blue, the involucral bracts all distinct and free. Sept. Asia.
Rochel. Leaves hairy-pubescent above, tomentose beneath (as also the stems), the lower ones deeply pinnately parted, the upper pinnatifid, spiny: flowers blue. Hungary. R.H. 1858, p. 519.
bb. Plant biennial. exaltatus, Schrad. Tall, the stem nearly simple and glandulose-pilose, the leaves pinnatifid, scarcely spiny: flowers blue. Russia. B.M. 2457 (as E. strictus, Fisch.). - Distinguished by its simple, erect stem The garden E. commutatus may be the same as this.
E. nivilis, Hort., is a trade name that is unknown in botanical literature. N Taylor-†