Rosidae: Apiales. The Apiaceae are mostly temperate herbs almost always with umbellate inflorescences comprising about 300 genera and 3,000 species that are commonly further distinguished by the presence of hollow stems and sheathing petioles. The leaves are nearly always alternate and pinnately or palmately compound or more than once compound; stipules are generally absent. The flowers are typically small, mostly bisexual, mostly actinomorphic except in a few instances where pseudanthia are produced and the peripheral flowers have enlarged petals directed away from the center of the inflorescence. The calyx is reduced to 5 tooth-like sepals around the summit of the ovary or may even be obsolete. The corolla consists of 5 distinct, typically inflexed petals or rarely is lacking. The androecium comprises 5 distinct stamens arising from an epigynous nectary disk. The gynoecium consists of a single compound pistil of 2 carpels, 2 styles borne on an enlarged stylopodium, and an inferior ovary with 2 locules, each containing a single pendulous, apical-axile ovule. The fruit is a schizocarp.
Each "thumbnail" image below is linked to a larger photograph.
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Coriandrum sativum, coriander. This species has the flowers arranged to form a loose pseudanthium that mimics a single flower. Notice that the peripheral flowers have one or two petals enlarged and directed away from the center of the umbel. |
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Cicuta douglasii, water hemlock. The rays of other portions of the compound umbel are barely visible in the background. Notice the 5-merous nature of the corolla and androecium, and the fleshy nectary disk and stylopodium around the base of the 2 styles in each flower. |
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Hydrocotyle verticillata, marsh pennywort. Although not visible here, this species is a rare example of the occurrence of simple leaves in Apiaceae. However, the inflorescence type and floral construction are still typical for the family. Notice the inferior ovary and the two styles per pistil. |
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Astrantium major. This species has showy bracts at the base of the umbel. It also has larger sepals than typical for the family. Note the small, pinkish inflexed petals and the inferior ovaries. |
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Sanicula sandwicensis, snakeroot. This endemic Hawaiian species has the umbels compacted into headlike inflorescences. The calyx lobes are more prominent than seen in many members of the family. The flowers are reportedly perfect or male although these appear to be male or female. |
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Eryngium foetidum. This genus has the flowers in heads rather than umbels. |