bulb or corm or tuber

This is an enormous and diverse plant genus. The onion family contains about 1250 species of herbaceous bulbous or rhizomatous plants that can be found across north temperate climates worldwide. All are perennials and cultivated forms are either grown for their ornamental flowers and foliage or as crops that yield edible greens and bulbs, such as onion, garlic, chive and leek. Species may be deciduous or evergreen and some are ephemeral.

Ornamental onions run the gamut from tiny groundcovers...

This excellent allium hybrid displays enormous, rosy-purple flower clusters on tall, sturdy stems in late spring to early summer. Its starry, individual florets are packed densely in rounded globes that can be as large as 8 inches (20 centimeters) in diameter, adding instant drama to mixed beds and borders. They rise from low rosettes of bold, strappy, deep green leaves that remain attractive while the plants are in flower, unlike those of many other alliums.

In autumn, plant the bulbs of ‘Beau...

This gorgeous ornamental allium graces the garden with globes of starry, silvery-purple blossoms in late spring. The rounded, softball-sized flower clusters are borne on sturdy, slender stems which rise above strappy, deep green basal leaves that emerge in spring and fade as the plants bloom.

In autumn, plant the bulbs of ‘Firmament’ in fertile, well-drained soil at a depth of two to three times their diameter. Full sun is essential, and dryish summer conditions are preferable. Plant in small...

A hybrid of two large-flowered Central Asian alliums, ‘Gladiator’ is a bulbous perennial grown for its huge globes of starry, metallic purple, green-eyed flowers displayed in late spring to early summer. The dense, rounded flower clusters are borne singly atop tall, sturdy, bare stems which rise above deep green, broadly sword-shaped basal leaves that emerge and spring and wither as the blossoms appear.

In autumn, plant the bulbs of ‘Gladiator’ in fertile, well-drained soil at a depth of two...

For many, ‘Globemaster’ is the standard against which all other ornamental alliums are judged. The gigantic, rounded, lavender-purple flowerheads of this hybrid are composed of small, starry, densely packed florets, and can approach the size of a volleyball. Appearing in late spring, they are borne singly on tall, sturdy stems which rise above bold, strappy, deep green basal leaves that appear in spring and fade as the plants bloom.

In autumn, plant the bulbs of ‘Globemaster’ in fertile, well-drained...

This attractive hybrid allium decorates the late spring to early summer garden with dense spheres of rich rosy-purple flowers. The rounded flowerheads are composed of many small, starry, individual florets, and are approximately 6 inches (15 centimeters) in diameter. They are borne on tall, strong stems which rise above strappy, green basal leaves that emerge in spring and fade as the plants bloom.

In autumn, plant the bulbs of ‘Lucy Ball’ in fertile, well-drained soil at a depth of two to...

This refined hybrid allium graces the late spring perennial border with globes of starry, shimmering white blossoms displayed on tall, slender stems. The baseball-sized flower clusters rise above strappy, deep green basal leaves that appear in spring and fade as the flowers emerge.

In autumn, plant the bulbs of ‘Mont Blanc’ in fertile, well-drained soil at a depth of two to three times their diameter. Full sun is essential for best flowering, and drier summer soil conditions are preferable....

Although this Central Asian native is rare in cultivation, many "drumstick alliums" - including the popular cultivar 'Purple Sensation' - are incorrectly sold under this name. Most bear large spherical heads of lilac-purple flowers on tall stems in late spring. The strap-shaped basal leaves wither shortly after the flowers appear.

These plants like rich, well drained soil and full sun. Use them as bedding plants or in mixed borders. They attract butterflies, and are relatively unpalatable to...

The ancestor of the cultivated leek is a bulbous perennial native to northern Africa, southern Europe, Turkey, Iran, and the Caucasus. Large umbels of lavender or red-purple flowers are borne in summer on tall stalks whose bases are sheathed by the withered remains of the long, strap-shaped leaves.

Plant the bulbs in full sun and fertile, well drained soil at a depth of two or three times their width. This ornamental onion is a natural for the herb or vegetable garden, but also works well in...

The tasseled flower clusters of this small bulbous perennial are one of the most charming signs that spring has arrived; the spreading carpets of blue bring cheer to gardeners everywhere. Shaggy tufts of purplish-blue sterile flowers appear at the tips of straight stems, above greenish brown fertile flowers. The flower stalks emerge in mid spring from basal clumps of fresh green leaves. This grape hyacinth is native to dry meadows in southern Europe, Iraq, and Turkey.

Plant the bulbs of tassel...