Common Arrowhead

The bedrock terrace I’ve been writing about supports a surprising number of wetland plants. This one, Sagittaria latifolia, is not only a wetland obligate, it’s an emergent: an aquatic plant that roots in shallow water and produces stems, leaves, and flowers above water level.

Typical of monocots, S. latifolia has floral parts in multiples of three, with three sepals and three petals. The flowers are typically unisexual, the male flowers having numerous yellow-anthered stamens, the females having numerous green pistils. In bisexual flowers, the stamens ring the pistils, as shown here. The flowers are usually borne on racemes, sometimes on panicles, with flowers in whorls.

Although S. latifolia is found in every state in the union except Nevada and Alaska, and in much of southern Canada, it’s most common in New England, the Mid-Atlantic, and the Upper Midwest. (It’s also in Hawaii, but considered alien there.) It’s endangered in Illinois, but considered weedy by the Southern Weed Science Society.

S. latifolia is in the Alismataceae, or water plantain family, which comprises anywhere from 80 to 120 species in about 15 genera, depending on which authority you consult. The Alismataceae is cosmopolitan, but most species are native to North America.

Common names include common arrowhead, wapato, wappata, and katniss. Some names refer to the plant’s appearance or habit: arrowleaf, bull-tongue, water-archer, water-lily, waxflower. Other names refer to edibility: Chinese-onion, duck-potato, muskrat-potato, swan-potato, swanroot, and tule potato.

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