This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Trees or shrubs, with bitter bark, and mainly alternate and pinnate not punctate leaves. Stipules minute or none. Inflorescence axillary, paniculate or racemose. Flowers regular, dioecious or polygamous. Calyx 3-5-lobed or divided. Petals 3-5. Disk annular or elongated, entire or lobed. Stamens of the same number as the petals, or twice as many; anthers 2-celled. Ovaries 2 - 5, or single and 2-5-lobed, 1-5-celled; styles 1-5. Seeds generally solitary in the cells; embryo straight or curved.
About 30 genera and 150 species, natives of warm or tropical regions, distinguished from Rutaceae mainly by their non-punctate foliage.