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.
Silky with fine appressed hairs; leaflets mostly linear; flowers larger (than Oxytropis campestris), purple, violet or sometimes white; pods cartilaginous or firm coriaceous in texture, strictly erect, cylindraceous-lanceolate and long-pointed, almost two-celled by intrusion of the ventral suture. (Gray's Manual of the Botany of the Northern United States.) when the reader notes that the botanical description of this beautiful wild flower is taken from Dr. Gray's Manual of the Botany of the Northern United States, which is confined to the "plants east of the Mississippi," he may be told that it is not properly at home in this region, but has merely disregarded geographical lines, and ran over a little into Dr. Gray's territory by way of western Minnesota. It is strictly a Rocky Mountain plant, extending from British America into Texas, leaving the higher elevations occasionally to adorn the plains below. It is wholly confined to this region, and has not even made its way to California as so many of the Colorado plants have done. The flowers of this dry region of our country have little odor, but they are famed for their brilliant colors, by which they give a gay and attractive feature to the otherwise dreary scenery of this inland tract. Among this brilliant assemblage our present species occupies no mean place. It forms tufts in the crevices of the rocks, or generally where the washings from higher places have made little patches of level land; and when it finds itself in these more favorable situations, it will sometimes throw up stems fifteen, or even eighteen, inches high. It is often much shorter than the specimen we have taken for illustration; but it has always the same showy head of flowers, thrown up above the silvery foliage, so as to be seen even from some distance away. Generally there are but two or three flower stems to a plant, but more are occasionally found. Sometimes the flowers are arranged in a denser head, and at other times more drawn out than in the illustration, and the leaflets are often broader and wider. In past times many of these variations have received distinctive botanical names, such as Oxytropis Plattensis, O. scricea, and O. Hookeri-aua; but these distinctions are abandoned now. In color there is much variation from purple to rose, and white is said to be not unfrequently met with, though the writer found but one such specimen in several weeks' collecting through South Park. The specimen illustrated was obtained from that place.
In the last century the species now referred to this genus were included among the milk-vetches or Astragalus. They were removed from this family in 1802 by Aug. P. De Candolle, who wrote a treatise especially devoted to this little family. Those which he called Oxytropis differed from the rest in having a sharp point to the keel or lower portion of the corolla, and which suggested the name for the genus from the Greek oxys sharp, and tropis keel. It seems a sharp point to found a genus on; but as the various species group well together, it seems sufficient to command general acceptance.
The species we now introduce was the first American of the genus discovered, all the others then known being natives of the old world. In 1825, when De Candolle published the volume of the "Prodromus," containing the order Leguminosa, there were forty-nine species known, but then only this one American among them. Now Mr. Watson, in his "Bibliographical Index," recognizes ten American species. It seems to have been first found by Mr. Thomas Nuttall, the early explorer of our Western country; but it was first named and described by Pursh in his "Flora Americanae Septentrinalis," issued in London in 1814. Pursh was never beyond the Mississippi; but without much scruple he seized on the labors of others whenever he had the opportunity, and passed them off as his own. Referring to the way in which he came to the knowledge of this plant Mr. Nuttall says, in his "Genera of North American Plants:" "Mr. Pursh's character is taken from a solitary luxuriant and cultivated specimen, which I obtained from seeds, and is inapplicable in nature;" which is well as affording an opportunity to show how Mr. Pursh became acquainted with the plant; but what is called cultivation does not change the characters of wild flowers to the extent the extract indicates. Our drawing was taken in 1878 from a plant growing in the garden since 1873; and on comparing the drawing with an herbarium specimen gathered in 1873 at the same place, no difference was apparent, not even in size; and this we find to be true in almost all cases. The specific name was given in honor of Mr. Aylmer Bourke Lambert, Vice-President of the Linnaean Society, who was one of the most accomplished botanists of that time. He was indeed the real editor of Pursh's work, and well deserves the honor which this connection of his name with an American plant may bring.
Though so interesting for the beauty it gives to Colorado scenery, it is a dangerous plant to cattle. From a California paper, the "Las Animas Leader," the following paragraph is taken: "This is a good country for cattle, but not for horses. The 'loco-weed' grows here in great abundance; and which when eaten by a horse kills it very soon after. Mr. Sheetz has seen a horse run for about a hundred yards and then drop dead. He believes it is not the plant, but an insect which is found on the under surface of the leaf that does the injury. Little Robe, the Cheyenne Indian chief, says positively that it is the small green insect which does the mischief. Describing the effect Mr. Sheetz says: 'After the animal has eaten the leaves for a little while, the animal seems much exhilarated. It is impossible to handle him. He will not drink water for four or five days. When horses commence to recover, water has to be given to them sparingly. When a horse is 'locoed' it is easily perceived.
Loco is a Spanish word, meaning mad, crack-brained, or foolish, which describes the effects of the weed on horses."
As already noted, the Oxytropis Lamberti is not recorded as being found by botanists in California, and if it is really not a native there, some other plant must have similar effects, supposing it to be the plant, and not an insect infesting it, which causes the injury. But Professor J. T. Rothrock, the botanist of Wheeler's Survey of the 100th meridian, believes that several kinds have been known as "loco-plants," though this seems to be the one he would pre-eminently give the title to in Colorado. He says: "Oxytropis Lamberti in Colorado, and Astragalus Hornii and Astragalus Ientiginosus, variety Fremontii, in California, are known as loco-plants. The term loco, simply meaning foolish, is applied because of the peculiar form of dementia induced in the animals that are in the habit of eating the plant. In Arizona, I was told the Hosackia Purshiana produces effects similar to the above plants, but I have no certain knowledge concerning it." In a note added before the work was finally issued the following observation is made: "The alcoholic extract of this plant failed, when hypodermically injected by Dr. H. C. Wood, to produce poisonous symptoms in the lower animals. He hence concludes it is a mistake to regard the Oxytropis Lamberti as one of the 'loco plants.'" Perhaps there may be some foundation for the Indian chief's suggestion that insects have more to do with the dementia than the plant itself; at any rate, it would be pleasant to know that a wild flower we cannot but admire for its beauty is devoid of all noxious qualities.
Its time of blooming seems to extend more or less over the whole season, judging by the reports of those who have found it. Its name occurs among the collections of most of the expeditions that have gone across the continent during the past fifty years, and though these have been at various seasons from June till October, it is generally reported as being gathered in flower.
1. A complete and average sized plant.
2. A spike with nearly mature seed vessels, from the same plant.