Hamamelidae: Urticales. The Urticaceae are monoecious or dioecious herbs or infrequently shrubs or small trees comprising 45 genera and 700 species, often with specialized stinging hairs. The leaves are alternate or opposite, simple, and almost always stipulate. The minute, unisexual flowers are in cymose clusters. The perianth is of mostly 4 or 5 undifferentiated tepals or is sometimes absent. The male flowers have a stamen opposite each perianth segment. The female flowers have a single simple pistil with a superior or inferior ovary that contains one basal ovule in its solitary locule. The stigma is brushlike and elongated or is capitate. The fruit is an achene or drupe; in a few species these coalesce to form a multiple.
Each "thumbnail" image below is linked to a larger photograph.
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Pilea microphylla, artillery plant. Numerous clusters of tiny greenish female flowers are visible. Though not very apparent, each has a tiny brush-like capitate stigma. A few larger, pinkish, mostly unopened male flowers are visible. These have four perianth segments and opposing stamens. | |||
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Urtica sp., nettles. Note the tiny greenish flowers and stinging hairs. | |||
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Neraudia melastomifolia, ma'aloa. Each female flower has a single, conspicuous, brush-like stigma. | |||
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Pipturus albidus, mamaki. Mamaki is one of the native Hawaiian species important as a source of fibers. The male plant in the upper photo has clusters of tiny staminate flowers. The staminate flowers (middle photo) have a 4-parted perianth with a stamen opposite each segment. A cluster of female flowers is shown in the lower photo. Note the single, brushlike, elongated stigma on each pistil. | |||
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Touchardia latifolia, olona, male inflorescence. In this species the flowers are 5-merous. |
