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.
(a Greek name for some sort of thistle). Umbelliferae. Eryngo. Sea-Holly. Annual and perennial herbs, chiefly valued for the steel-blue or pur-Elish cast of their rigid stems, prickly foliage and teasel-ke heads.
Rarely shrubby: leaves stiff or coriaceous, undivided, lobed or pinnatisect, the margin nearly always spiny: flowers small, white, greenish or blue, sessile or subsessile, bracteolate, in involucrate heads or spikes; calyx-teeth prominent, mostly rigid, sometimes ending in a spine-point; petals erect; disk expanded; styles slender: fruit ovoid or obovoid or more or less globose, scaly or tuberculate, without ribs, the carpels nearly terete and with usually 5 oil-tubes. - Wolff estimates (in Engler's Pflanzenreich, hft. 61, 1913) 220 species, widely dispersed in warm and temperate regions with the greatest extension in the Medit. region.
There are two very distinct groups of eryngoes, one with much-cut foliage, as shown in Fig. 1417, the other the "pandanus group" (of the New World), with long undivided leaves. The species are little grown in this country, but they are more used abroad. They produce striking semi-formal and often somewhat bizarre effects. They are used in subtropical bedding, particularly the large pandanus-leaved kinds. They are excellent for borders and rock-gardens, being prized particularly for their colored stems and often brilliant involucre. The stiff leaves of the pandanus group are little damaged by weather. The dried stems retain their color, and are sometimes hung in living-rooms. The plants mostly grow from 2 to 3 feet high and head out in July to September. A light rich soil and sunny situation are advised. Poor drainage is to be avoided. E. amethystinum is probably the most popular species in this country. E. planum is said to be much visited by bees. They are slow to recover from the shock of division. This makes it difficult to work up a stock at home sufficient to make an effective group. The only safe way to increase them is by seed. The seed may be sown as soon as gathered. They will germinate in the spring, and should be ready to plant out the following year.
Some of the species self-sow. The species described below are perennial.
Fig. 1417. Eryngium amethystinum. (X 1/2) cc. Nerves of If. parallel, prominent.
a. The pandanus-leaved group. b. Bracts of involucre long and prominent.
1. agavifolium, Griseb. Becoming 6 ft. high in its native country: stem simple below and somewhat branched above, 3-forked at top: basal leaves rosulate, ensiform, to 5 ft. long, coarsely spinose-serrate: head cylindrical, about 2 in. long and half as thick; the involucral bracts 10-16, ovate at base and gradually narrowed, entire or sparsely spinulose; sepals round-ovate or nearly-orbicular; petals obovate or elliptic-oblong. Argentina, blooming Jan. - March. G.W. 15, p. 477.
2. bromeliaefolium, Delar. Becoming 9 or 10 ft. tall, the stem about 4-forked at top: basal leaves numerous, 1 1/2 ft. and more long, narrow and very acute, the margins subulate-dentate, spine-pointed: head ovoid or ovoid-cylindrical, about 1 in. long; involucral bracts many, rigid, unequal, linear-subulate, pungent-pointed; sepals ovate-lanceolate, short-acuminate and mucro-nate. Highlands, Mex.; Dec.
3. protaeflorum, Delar. Plant very stout, 3 ft. and more, the stem fistulose and sulcate: stem - leaves very stiff, the upper ones 8 in. or more long, linear-lanceolate, long-acuminate and pungent-pointed, the margin subulate-spinose: head ovoid-cylindrical, 2 1/2 in. long; bracts of involucre very many and very rigid, in several series, lanceolate and sharp-pointed; flowers very many; sepals broad-ovate, obtuse, short-mucronate; petals white, obovate-spatulate. Mex. Sept. G.C. III. 41:248,249. Gn. 75, p. 380.
bb. Bracts of involucre scarcely prominent, not very stiff. c. Nerves of If. diverging.
4. aquaticum, Linn. (E. yuccaefblium, Michx.). Button Snakeroot. Rattlesnake Master. Height
2-6 ft.: stem striate, unbranched or branched above: leaves undivided, long and linear, rigid, mostly clasping, finely parallel-veined, lower sometimes 3 ft. long, 11/2 in. wide, all bristly margined: heads globose-ovoid. Wet soil, E. U. S.
5. Lassauxii, Decne. Height 3-6 ft., thest. fistulose, 3-forked at top: basal leaves often slightly twisted, canaliculate, to 2 in. wide, long-acuminate, the margin spiny: heads in a broad corymb, each one small, about 1/2in. through, whitish green; involucre-bracts ovate- lanceolate, spinulose - ciliate; sepals nearly orbicular or 4-angled-orbicular, truncate and erose; petals rectangular-ovate. S. Brazil, Paraguay, Uruguay. G.W. 3, p. 549.
6. pandanifolium, Cham. & Schlecht. stem to 8 ft. high, leafy, 3-4-forked above: basal leaves 4-5 ft. long, spine margined above; stem - leaves many, to 1 1/2 ft. long, spiny; heads colored, globose-ovoid, less than 1/2 in. long, in large panicles; involucral bracts broad-ovate, very acute, rough on the back; sepals nearly orbicular or oval, short-mucronate; petals dark purple, ovate or orbicular-oblong. S. Brazil, Argentina. Gn. 61, p. 37. G.W. 4, p. 197.
7. eburneum, Decne. (E. bracted-sum, Griseb.). Height 8 ft., from -a thick rhizome, the stem ivory-white: basal leaves crowded, canaliculate, 3 ft. and more long, acuminate, very spiny, the spines being slender: heads not colored, ovoid or globose-ovoid, 3/4in. long; involucral bracts triangular or lanceolate or linear; sepals ovate or oval, obtuse or short-acuminate; petals somewhat rectangular - oblong, fimbriate at apex. S. Brazil, Uruguay, Argentina.
aa. The cut-lvd. group (or leaves, at least on st, broader, more or less toothed, and not pan-danus-like).
b. Leaves fleshy.
8. maritimum, Linn. Glaucous-blue, stiff, much-branched, about 1 ft. high: leaves very stiff, broad, sinuate, more or less3-lobed, handsomely veined, with coarse prickly teeth, those on the stem clasping, the radical ones petioled: heads nearly globular, pale blue; involucral bracts 5-8, much smaller and narrower than the stem - leaves; sepals ovate-lanceolate; petals oblong. Seacoasts of Eu. Gn. W. 15:489.
bb. Leaves not fleshy. c. Basal leaves usually not lobed (or not prominently so).