This lifeform is found widely in Africa. This lifeform is found widely in Eurasia. This lifeform is found widely in the Indo-Australian region. This lifeform is widespread in North America. This lifeform is found widely in the New World tropics. This lifeform is frequently domesticated. This lifeform is grown commercially for human food.

Commercial onion (Allium cepa) is not known in the wild.

The Allium genus (Onion and garlic) is native to  the Northern Hemisphere.  Many of the popular garden and agricultural plants in this genus are now established in the Southern Hemisphere.  There are about 700 species of perennial and biennial herbs in this genus.  These plants are typically odorous with bulbs as a key part of their root system.  The leaves are usually linear, but maybe lanceolate. There are almost 100 species with another 50 subspecies and varieties now established in greater North America.

Lilies (Family Liliaceae) are usually characterized by having flowers with three (or six) petals that have radial symmetry. There are over 4,600 species divided into over 600 genera in this widespread family. North America has about 520 species in almost 90 different genera. (The North American numbers are based on the inclusion of the Amaryllis group with the lily family.)

Here this family has arbitrarily been divided into several subgroups. These groups are the wild lilies of different geographical areas: the Aloe group, and lilies cultivated as ornamentals, or vegetables. The placement of several of the well-known species in both the wild and in the garden has been arbitrary.

Lily Order (Order Liliiflorae) contains several families many of which are noted for their beautiful flowers. In addition to the rushes, this order contains the well-known lily family. Although some authors combine them with the lilies, here the Amaryllis, Iris, and Agave groups are presented in separate families.

Monocots are a large group of plants usually characterized by having leaves with parallel veins and a seed with a single shell. Most flowers are created with multiples of three. In  the older botany texts, the Monocots were considered more primitive than the Dicots. However, many recent authors have placed the Monocots as an offshoot of the primitive Dicots. Here they are placed before the Dicots.

Seed plants (Phylum Embryophyta) are generally grouped into one large phylum containing three major classes: the Gymnosperms, the Monocots, and the Dicots. (Some scientists separate the Gymnosperms into a separate phylum and refer to the remaining plants as flowering plants or Angiospermae.)

For North American counts of the number of species in each genus and family, the primary reference has been John T. Kartesz, author of A Synonymized Checklist of the Vascular Flora of the United States, Canada, and Greenland (1994). The geographical scope of his lists include, as part of greater North America, Hawaii, Alaska, Greenland, Puerto Rico, and the Virgin Islands.

Kartesz lists 21,757 species of vascular plants comprising the ferns, gymnosperms and flowering plants as being found in greater North America (including Alaska, Hawaii, Greenland, Puerto Rico and the Virgin Islands).

There are estimates within the scientific world that about half of the listed North American seed plants were originally native with the balance being comprised of Eurasian and tropical plants that have become established.

Plant kingdom contains a large variety of different organisms including mosses, ferns, and seed plants. Most plants manufacture their energy from sunlight and water. Identification of many species is difficult in that most individual plants have characteristics that have variables based on soil moisture, soil chemistry, and sunlight.

Because of the difficulty in learning and identifying different plant groups, specialists have emerged that study only a limited group of plants. These specialists revise the taxonomy and give us detailed descriptions and ranges of the various species.  Their results are published in technical journals and written with highly specialized words that apply to a specific group.

On the other hand, there are the nature publishers. These people and companies undertake the challenging task of trying to provide easy to use pictures and descriptions to identify those species.