Both orchids and lilies produce showy flowers that catch the attention of gardeners and florists. In botany, both orchids and lilies are classified as flowering plants, or angiosperms, and monocots. After that basic relationship, orchids and lilies separate into distinctly different groupings. The name orchid is applied to any plant in the orchid family, Orchidaceae. Lily is a name most correctly assigned only to plants in the genus Lilium, although many other plants in the lily family, Liliaceae, or other plant families are colloquially called lilies.
Orchids comprise the largest plant family on Earth -- 25,000 species and over 100,000 manmade hybrids known as grexes. The orchids grow worldwide in a variety of habitats from tropical rainforests to desert and tundra. They are further placed in similar groupings or genera, which number around 800, such as Cattleya, Phalaenopsis or Cypripedium. By contrast, lilies are all placed in the genus Lilium, comprising some 100 species. They grow in woodland habitats in the temperate Northern Hemisphere. In addition, hundreds of hybrids exist that were developed by horticulturists.
Orchids grow in a variety of forms. Most are fleshy-rooted plants known as epiphytes that clasp onto trees. The roots are either horizontal and swell into false bulbs that sprout leaves or are slender roots that sprout leaves from these root tips. Some orchids also grow from bulblike tubers and rhizomes that grow in soil. Lilies grow from ground-dwelling bulbs and produce upright stems with leaves. The bulbs are fleshy and made up of overlapping scales. Rarely, lily bulbs grow with spreading underground stems called stolons.
The only common bond among orchid and lily flowers is that flower parts occur in multiples of three or six. Orchid flowers are highly modified or specialized in form compared to other plant families. Orchids often have one petal shaped like a lip adjacent to the flowers' central sex organs. Flowers have various types of symmetry. The specialized orchid flower shape and structure is for specific pollination by an animal or insect. Orchids often evolve and develop in a close relationship with a pollinator. Lilies, on the other hand, are wide-opening trumpet, cup, bowl, bell or platter shapes. The six petals equally surround or radiate from the central sex organs. They are pollinated by any area insects that seek pollen or nectar.
Confusion in Comparisons
The orchid family is so large and diverse that some orchids look just like true lilies. These orchids may be commonly known as a lilies, such as those in the orchid genus Tricyrtis called toad lilies. Moreover, more genera in the lily family are known as lilies, such as the daylily (Hemerocallis), plantain lily (Hosta), trout lily (Erythronium) and Peruvian lily (Alstroemeria). Even plants in other families are called lilies: calla lily (Zantedeschia), waterlily (Nymphaea), Mexican and Barbados lilies (Hippeastrum) and rain lily (Zephyranthes). From a botanical standpoint, these other lilies differ from true lilies in their flower structures.