The Rutaceae are herbs, shrubs, and trees with glandular punctate, commonly strongly smelling herbage comprising about 150 genera and 1,500 species that are further characterized by the common occurrence of spines and winged petioles. The leaves are alternate or opposite, simple or palmately or pinnately compound, or sometimes heathlike or reduced to spines; stipules are absent. The flowers are often sweet-scented, nearly always bisexual, and are actinomorphic or sometimes zygomorphic. The calyx consists of 3-5 distinct or basally connate sepals and the corolla consists of 3-5 distinct or sometimes connate petals or rarely the petals are lacking. The androecium consists of distinct or sometimes connate stamens that are commonly obdiplostemonous, that is in two whorls with the outer whorl opposite the petals. However, sometimes there may be (1)3-4 whorls or rarely up to 60 stamens. The gynoecium consists of a single compound pistil of commonly 2-5 or more, often incompletely connate carpels that may be united only basally or apically, either one or an equal number of styles, and a superior ovary with usually 2-5 or more locules, each bearing 1-several axile ovules. Generally, an intrastaminal nectary disk is situated between the stamens and the ovary. The fruit is variable.

Each "thumbnail" image below is linked to a larger photograph.

Casimiroa edulis, white sapote. Small tree from Mexico and Central America, with somewhat apple-like fruit about 3 inches in diameter. The skin is thin, green or yellow, enclosing a soft, juicy, edible sweetish pulp. In Mexico, the bark, leaves and seeds are used medicinally to induce sleep.
Choisya ternata, Mexican orange blossom, ornamental, Corvallis, OR, October 19, 2005.
Citrus aurantifolia, Mexican lime.
Citrus limon, lemon.
Citrus maxima, zabon, pummelo.
Citrus medica, Buddhas hand.
Citrus paradisi, grapefruit. Oil glands are clearly visible on the fruit. Note also winged petioles, superior ovary, well developed nectary disk, and numerous stamens.
Citrus reticulata, tangerine.
Diosma ericoides.
Fortunella sp, kumquat.
Geijera multiflorum. Note the yellow nectary disk between the stamens and ovary. In this case only a single whorl of alternate stamens are present.
Melicope sp., alani. Notice the stamens twice the number of petals and the conspicuous yellow nectary disk in this native Hawaiian species.
Murraya koenigii. Note the glandular dots on the petals.
Murraya paniculata, mock orange. Small tree or shrub from India to Malaya. This common hedge planting bears sweet-scented white flowers about half an inch across, and similarly sized inedible red fruits resembling miniature limes.
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Platydesma spathulata, Rutaceae, pilo kea, Hawaiian endemic.
Triphasia trifolia, lime berry. Spiny shrub from southeast Asia. Note the glandular-dotted leaves common in the family. This species is obdiplostemonous, meaning it has two whorls of stamens with the outer whorl opposite the petals, a condition common in this and a few other families.

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