This section is from the book "The Native Flowers And Ferns Of The United States ", by Thomas Meehan. Also available from Amazon: The Native Flowers and Ferns of the United States in Their Botanical, Horticultural, And Popular Aspects.
Stem erect, sulcate, sparingly branched; lower leaves oblong-ovate, repand-dentate, upper ones lanceolate, acute, all sessile and glabrous; heads few or solitary, very large; pedicel thickened at the summit; ray flowers twice longer than the disk; scales with a pectinate-pinnate, reflexed appendage. Stems two to four feet high, with large, showy, pale-purple heads. Appendages straw color. (Wood's Class-Book of Botany.)
OUR text-books tell us that " Centaurea was so named from Chiron, the centaur, who first discovered the medical virtues of the plant." It may be remarked here that ancient history is so mixed - that which may be true confused with that which is mere fancy - that we are liable to take the whole of ancient history as of little account. As we generally understand the "centaur" we have the fable of Ovid in mind, wherein the daughter of a goddess in pity is changed into Enippe - half woman, half horse - in company with the half-beast centaur already existing, - but it appears from those who have made ancient history a study that certain Thessalonians first tamed horses so as to ride upon them, and thus appeared to their frightened neighbors, who observed them at a distance, as beings who were part horses and part men. Out of this it is supposed the fables come. One of these Thessalonians, "a centaur" named Chiron, was seriously wounded by Hercules; but by the discovery of the healing virtues of some plant he saved his life.
This Chiron appears to have been a veritable personage, but the plant he found is a sort of gentian, referred to by Breyne, who wrote a work called "Centuria Plantarum," in 1678, as Chiironia, which name was adopted by Linnaeus as Chironia Centaureum, and is believed to be the Centauria of Dioscorides, and also the plant which should be identified with Chiron's history. The genus which we now call Centaurea, and to which our present species belongs, contains the plant which seems to have been referred to under this name by Theophrastus, a Grecian author who died 288 years before Christ, by Lucretius, and by Virgil; and which is now Centaurea Centaurium, but how it is connected with "Chiron, the centaur," is not clear. The earlier of extant English authors on Botany seem unable to unravel the puzzle, so for distinction they called the gentians the " lesser centaury," and those which we now refer to the genus the "greater centaury." Instead of being able to heal a wound, such as that from the poisoned arrow from which Chiron suffered, these plants have no medical value whatever.
The genus contains numerous representatives in the old world, but in the new has but a single indigenous species, Centaurea Americana, the one we now describe; and this is confined in the United States to the dry regions of Texas, Arkansas, and the Indian Territory, where it has a singularly beautiful appearance, being often the only showy plant on the dry sterile soil, for the pretty ones are generally to be found only along the water courses, or where in low places the ground may be moist. Still it has no objection to more favorable locations under other circumstances, as its luxurious growth and fine blossoms when under garden culture show. At least this dry location is the experience of the writer of this, who collected it in northern Texas. In the " Plantae Lindheimerianae," where it is marked as being found near Houston, in Texas, it is noted as growing in "moist, fertile prairies." Rothrock, in the botany of the Wheeler Expedition, notes its collection in Arizona, but does not give the nature of its location. It varies somewhat, and the particular form we have illustrated, first collected by Mr. Elihu Hall in Texas, is known as the " Variety Hallii."
Our plant is of particular interest on account of its botanical features, as well as for its native beauty, and its easy adaptation to grarden culture. As the student knows, the bracts which go to make up the involucral scales in this natural order, and which in this Centaurea have a pretty comb-like appearance, are but leaves which have been suddenly and nearly suppressed. The whole head of flowers is indeed a long stem which has been drawn into a small compass, as would be a wire spring pressed down. One phase of stem growth ceases when the flower begins to form. The flower is indeed the effort of a second Growth-wave, and, instead of the leaves winding round the branch as in the first wave of growth, the changed leaves and axillary buds as scales and flowers, wind round the receptacle. Now in view of this morphological law we might expect the numerical parts in the second wave to accord somewhat with the first, - that is to say, a plant with leafy stem should have a great number of involucral scales or other floral parts. We do not always see this correspondence, because the parts will often be wholly absorbed, united with each other, or suppressed; but we often may, and it is especially to be seen in the case of the American Centaurea, which has a very leafy stem, and a correspondingly numerously-bracted involucre. Again, the pectinate, or comblike appendage to the scale, is interesting as showing a power in the genus to have pinnately parted leaves. There is nothing else to indicate this power in this particular species, for the leaves are remarkably entire; that is, showing no indications of any lobes or parting along the edges. But on seeing these pin-natifid bracts, and knowing what we now know of their typically leafy character, a student meeting this species for the first time he ever saw one of the genus, might fairly expect to find pinnately parted leaves in some of them. And this he really may do, for there are other species with such divided leaves. The much swollen upper portion of the hollow stem is extremely interesting. The numerous grooves in this portion give some indication of the great numbers of primordial leaves which have gone to make up this huge compound flower. The normal growth of a stem of a composite is made up of a spiral of five leaves; as these over-lap in the growth-coil the outer edge of each leaf makes a light ridge. There are, therefore, five distinct ribs in many composite stems, and which when the stem is cut across so often give it a five-angled appearance. As the spiral has not been drawn out in forming the head as in the stem growth, the united bases of the leaves cannot take on the five-angled plan, but are numerously arranged around a common centre, and afford us some idea of their great number by the little ridges we see.
1. Opening flower.
2. Nearly mature flower, showing the involucral scales.
3. Floret with young achene at the base.
4. Scale from the inner part of the flower.
5. Scale from the exterior.