Weeds in the Urban Landscape by Richard Orlando

Author:Richard Orlando
Language: eng
Format: epub
ISBN: 9781623172121
Publisher: North Atlantic Books
Published: 2018-03-10T05:00:00+00:00

Onions, garlic, chives, and leeks, as well as the various “wild onions” that grow in woods and meadows and are sometimes planted as ornamentals, used to be classified as members of either the lily family (Liliaceae) or the amaryllis family (Amaryllidaceae), but were split out into a family of their own, the Alliaceae, when a massive revision of the enormous lily family and the closely allied Amaryllidaceae was completed in the late 1990s. These plants are monocots, with long, narrow, entire leaves, and flowers in clusters atop a stalk known as a scape. Many have long histories as cultivated plants, grown for culinary, medicinal, and ornamental purposes. Some are weeds.

Allium triquetrum, the wild onion (it could be called the three-cornered onion), is a Mediterranean allium that spreads aggressively in urban gardens and open spaces, especially in moist locations. Growing from a bulb, it forms a plant about a foot tall, consisting of upright, linear leaves about 3/8 inch wide, with a prominent midrib; the lower portions of these leaves are somewhat triangular in cross section. The flower scape, a little taller than the leaves, is also three-sided, and it is capped by an umbel of drooping, pure white, bell-shaped flowers with green markings. Leaves and bulbs are onion scented, with some garlicky overtones. They can be eaten, if you find them palatable.

These wild onions are very attractive when they first appear in the garden, and you might be tempted to leave them—do not succumb to this temptation. Growing from bulbs, these weedy onions are perennial—and the bulbs produce many offsets. The flowers engender oval, three-lobed seed capsules, which release multitudes of black, wrinkled, readily germinating seeds. Once Allium triquetrum has entered a garden, it will most likely always be there; if it is not dealt with quickly and firmly, it will take over. Intervening early and often will keep it to a manageable level. A translocated herbicide such as Roundup can be helpful in reducing severe infestations, but it will not control the offsets—patient, persistent digging is always required.

The Neapolitan onion is an attractive allium that is often planted as an ornamental but tends to spread freely and move from garden to garden. It is not nearly the menace Allium triquetrum is, and it is worth learning to distinguish it from the three-cornered onion. Neapolitan onion is a taller, more graceful plant, with a long, sometimes slightly curving flower stem, round in profile. The individual flowers that form the umbel are open, on longer pedicels, and face upward. These mix very nicely with blue flowering plants that bloom at about the same time (mid-March on the California coast), such as Spanish bluebells (Endymion hispanicum) and pride of Madeira (Echium fastuosum). Both these plants can also spread quite freely.

Perhaps the most menacing wild onion is false garlic, a plant with narrower and darker green leaves than A. triquetrum and A. neapolitanum, no fragrance, and clusters of dull white flowers with greenish bases and reddish ribs on the outsides of the petals. These blooms are fairly small and generally brownish in appearance.

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