The Lily Family (Liliaceae) is one of the less common plant families in Rocky Mountain National Park, with only 15 species known from the park. Lilies are, however, some of our most beautiful flowering plants.
World-wide there are about 280 genera and 4,000 species of lilies. Most are herbaceous meaning that they do not have woody stems, and that they die back after they have flowered and fruited. They are all perennials- they live from year to year. All have three petals, three sepals (the structures that cover the outside of the flower bud,) and six stamens (see labeled picture.) In some cases the petals and sepals are indistinguishable, while in other cases they are noticeably different. Their leaves are usually narrow and all leaves have parallel veins. The leaves are usually alternate, though some lilies have opposite leaves or leaves in whorls. The fruit is either a dry capsule or a berry. Most lilies have bulbs or other underground storage organs and in some cases these, or the shoots, are edible. Onions, leeks, and asparagus are examples. In other cases, such as Death camas, they are poisonous.
In Rocky Mountain National Park Wood lilies (Lilium philadelphicum) bloom from July, Mariposa or Sego lilies (Calochortus gunnisonii) from early July to mid-August, Glacier or Avalanche lilies (Erythronium grandiflorum) from mid-May to mid-August (depending on altitude), Alplilies (Lloydia serotina) from mid-June to late July, Sand lilies (Leucrinum montanum) from early May to early June, and Twisted-stalks (Streptopus fassettii) from mid-June to mid-August.