Yarrow, Milfoil, Nosebleed, or Sneezewort; a genus of the order of the polygamia superflua, belonging to the syngena clafs of plants. The natural order to which it belongs is the 49th, Compositae difformis.
The characters are: The common calyx is ovate and imbricated, with ovate, acute, converging scales. The compound corolla is rayed; the hermaphrodite corollas are tubular in the disc, the feminine linguisiform and from 5 to 10 in the rays: The proper corolla of the hermaphrodites is funnel-shaped, expanded, and divided into 5 segments; that of the females, tongue-shaped, inversely cordated, expanding, and of 3 segments. The stamina in the hermaphrodites consist of 5 very short capillary filaments; the anthera is cylindric and tubular. The pistillum in the hermaphrodites has a small germen; the stylus is filiform the length of the stamina; the stigma is obtuse and end-notched: in the females, the germen is small; the stylus is filiform; the stigma are 2, obtuse and reflected. The pericarpium is wanting; the calyx scarcely changed; the receptacle filiform, elongated at the disc of the seeds, ovate, and twice as long as the calyx. The seeds are solitary, ovate, and furnished with a lock of wool; no pappus. The receptaculum is chaffy and elevated.
Species and properties. There are 20 species, of which the following are the principal: 1. The milfoilum, or common yarrow, is found naturally on banks, and by the sides of foot-paths, in most parts of England. It most commonly bears white flowers, though a variety of it is found which bears purple ones. These, however, do not long continue to bear flowers of this colour, if transplanted into gardens. It was formerly used in medicine; but though it may still have a place in some dispensaries, no physician of any note expects any virtue from it, or ever prescribes it. It creeps greatly by its roots, and also multiplies by the seeds, so that it becomes a troublesome weed where it is once allowed to get a footing. The cultivation of it is recommended by Mr Anderson, in his Essays on Agriculture, as a proper food for cattle. This species was the proper achillea of the ancients, so named from Achilles; who, having been the disciple of Chiron, first brought it into use for the cure of wounds and ulcers.
2. The santolina, or eastern sneezewort, is sometimes cultivated in gardens; it has large yellow flowers, which stand upon pretty long footstalks placed singly, not in bunches as in the common kind. It has leaves like lavender-cotton, which, when rubbed, emit a strong oily odour. The flowers appear in June and July.
3. The tomentosa, or woolly yarrow, is a native of the south of France and Spain, but lives in the open air in England. The flowers are of a bright yellow, and continue long in beauty, growing in clumps at the top of the stalks, which seldom rise above a foot high. The leaves are finely cut, and very hoary.
4. The abrotanifolia, or tall eastern yarrow, is a native of the islands in the Archipelago: it grows to the height of two feet and a half, with large umbels of yellow flowers on the top; the leaves resemble those of the common wormwood, and are cut into long narrow segments.
5. The clavenna, or Alpine umbelliferous wormwood, takes its name from the mountains of which it is a native. It seldom grows above six or seven inches in height; it supports umbels of white flowers, like those of the common sneezewort, which appear in April and May. The leaves are silvery, and shaped like those of wormwood, which often decay in the autumn and winter.
6. The tanacetifolia, or eastern sneezewort, with tansey leaves, is a very humble plant, seldom rising above six inches in height. The flowers are nearly as large as those of the common sneezewort, white, and growing in flat umbels. They appear in June and July. The leaves of the plant have some likeness to those of the common wormwood, are very hoary, grow close to the ground, and decay in autumn so as to make little appearance in winter. Like the last species, this is a native of the Alps.
7. The ageratum, or sweet maudlin, was formerly much used in medicine and for culinary purposes, but has now fallen into much neglect as to be totally unknown in the markets; so that when it is demanded, the white maudlin is substituted in its stead. The reason of this substitution was, that the latter is more hardy and easily propagated than the sweet maudlin, which is apt to rot in wet winters. The common maudlin flowers in June and July, and the seeds are ripe in September.
8. The Egyptian, or hoary sneezewort, is a native of the Archipelago. It hath very hoary leaves, which remain all the year; and the plants growing close and low, make a pretty appearance at all seasons. The flowers are yellow, and are produced in umbels on the top of the stalks; they appear in June, and continue till the end of September.
9. The ptarmica, or common sneezewort, grows wild in the woods, and other shady places, in many parts of England; so is not admitted into gardens. There is a variety, however, with double flowers, which is preferred in gardens, and is commonly known by the name of double maudlin. This species creeps greatly by the roots, so as soon to overspread a large spot of ground. If planted in pots, so as to confine its roots from creeping, the stalks grow close together, and make a tolerable appearance when in flower; but when at a distance, so that the roots have full liberty to run, the flowers appear but indifferently.
10. The macrophylla, or Alpine sneezewort, with fewer leaves, is a native of the Alps. It produces many stalks rising near three feet high; having loose branching umbels of white flowers on their top, resembling those of the common sneezewort, but larger.
11. The nana, or hoary Alpine milfoil, is likewise a native of the Alps; the leaves are hoary, and the umbels of its flowers are more compact than the former; the stalks do not rise more than a foot high.
12. The nobilis, or sweet milfoil, approaches to the nature of the common milfoil; but its leaves are of a paler green, and are neither so long nor so much cut off as those of the common milfoil are: they have a strong sweet scent when bruised.
13. The alpina, or white maudlin, bears some resemblance to the common sneezewort; but the leaves are longer, of a deeper green colour, and deeply indented in their edges; the flowers are white, and the roots creep far under ground. The plant will rise, in good land, to the height of four feet.
Culture. All the sorts of yarrow are easily propagated by seeds, which may be sown either in the spring Achilleid, or autumn, upon a bed of common earth. When the plants come up, and are strong enough for transplanting, they should be planted in beds in the nursery, where they may continue till autumn, when they should be transplanted to the places where they are to remain. The Archipelago kinds, however, are often destroyed by severe frost; so they ought to be sheltered during the winter. These kinds also rarely bring their seeds to perfection in England; they are therefore to be propagated by slips, which may be taken off and planted in a shady border any time in summer, when they will take root in about six weeks, and then may be transplanted where they are to remain.