The Morton Arboretum's Naturalist Certificate Program
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Local Flora I: Spring Woodlands | Grasslands | | Glossary: Plant Parts | Flowers | Leaves Monocots | Liliaceae | Other Monocot spp. | | Dicots | Ranunculaceae | Other Dicot spp.
Featured family: Liliaceae Lily Family	Monocotyledons - Class Liliopsida Definition: Plants which produce on the germination of the seed, a single "seed-leaf" or cotyledon.
	Monocots include many plants familiar to us such as lilies (Liliaceae), irises (Iridaceae), and orchids (Orchidaceae). The gramineous plants, including grasses (Poaceae) and sedges (Cyperaceae), account for 24% of the native plants around Chicago. Monocots are usually recognized by their long slender grass-like leaves, flower parts often in 3's or 6's (there are exceptions), and stems typically with scattered vascular bundles. There is less diversity in growth forms in the monocots, due primarily to the lack of a vascular cambium. As a result, nearly all monocots are herbaceous (exceptions are some Smilax and Yucca species with somewhat woody stems). Monocots include the world's smallest flowering plants: Wolfia, water meal, and other duckweeds.
	Except in Trillium, Medeola, Smilax, some aroids, and Dioscorea the leaves are all parallel veined. Leaves are often sheathed at the base. Leaf arrangement is frequently basal or alternate, rarely opposite or whorled (some Liliaceae, e.g., Trillium). Stipules are generally absent. Underground structures are often bulbs or corms although rhizomes and fibrous roots are not uncommon (especially in grasses). Sometimes the covering of bulbs is intricately sculptured and this is an important identifying character.
	Flowers are borne either from axils or terminally and may be solitary or arranged in various types of inflorescences, including cymes, corymbs, umbels, spikes, racemes, panicles or even heads. The flowers are usually perfect, i.e., have both male and female parts. Some exceptions are Asparagus, Smilax, Arum and Dioscorea species. Dioscorea are also dioecious, i.e., have male and female flowers on separate plants.
	The perianth is not well differentiated into calyx and corolla (except Trillium). The predominant number of perianth parts per flower is six, (in Maianthemum the perianth is reduced to 4 segments). These perianth parts may be free, united at base, or united into a tube. The flowers are mostly radially symmetrical (actinomorphic) Some of the orchids have a modified petal (lip) and are therefore zygomorphic (bilateral symmetry). The number of fertile stamens often is 3 or 6 per flower. Some of the exceptions are Orchidaceae with one and Maianthemum with 4. Most families have single pistils and superior ovaries. Orchidaceae, Burmanniaceae, Hydrocharitaceae, Iridaceae and Dioscoreaceae have inferior ovaries as well as some Liliaceae.
	The fruit type for most families is the capsule, but some have a cluster of follicles or an achene and others have utricles or drupe-like fruits.

Edna Davion Department of Botany, The Field Museum Chicago, IL 60605-2496 E-mail: edavion@fieldmuseum.org

Photographs by Jane and John Balaban Skokie, Illinois North Branch Restoration Project