Dilleniidae: Ericales. The Ericaceae are mostly shrubs comprising about 125 genera and 3,500 species. The leaves are simple and alternate or sometimes opposite or whorled; stipules are absent. The flowers are bisexual and actinomorphic or sometimes slightly zygomorphic. The perianth is in two whorls, a 4-7 merous calyx of usually connate sepals, and a 4-7 merous corolla of usually connate petals. The androecium has as many, or more commonly, twice as many stamens as corolla lobes or petals. The anthers dehisce by terminal pores and pollen is usually released in tetrads. The gynoecium consists of a single compound pistil of 2-10 carpels, usually a single style, and a superior or inferior ovary with 2-10 locules, each bearing numerous axile ovules. The fruit is a capsule or berry.
Each "thumbnail" image below is linked to a larger photograph.
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Rhododendron sp. The calyx in this genus is commonly very reduced. It is just visible as a yellowish rim at the base of the ovary of the immature fruit at the upper left. The tubular base and spreading lobes of the corolla of the open flower are clearly visible, as are the 10 stamens, each with terminal pores releasing white pollen from the orange anthers. The greenish style with its enlarged stigma is also exserted from the corolla. |
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Rhododendron indicum, azalea. This species has somewhat zygomorphic flowers. The terminal anther pores are barely visible in this photo. |
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Rhododendron sp. |
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Vaccinium reticulatum, 'ohelo. The inferior ovaries that are typical of this genus can be seen in this endemic Hawaiian species. The inverted urn-shaped or urceolate flowers illustrated here are common in several genera of the family. |
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Arbutus menziesii, Pacific madrone. This cut away view reveals the internal arrangement typical of the urceolate flowers of the family. Insects probing into the open end of the corolla contact the appendages on the anthers and this causes the pollen to sift out of the terminal pores onto the body of the visitor. The pistil is clearly visible in the center of the sectioned flower. |
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Gaultheria shallon, salal. |
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Cassiope tetragona, white or mountain heather. |