Word of the Week: Peltate

peltate [ pel-tayt ] adjective: 1. describing a flat surface, usually a leaf, which has its stalk or petiole attached at the center of the lower surface rather than at the edge or base 2. shaped like a shield

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Plants with peltate leaves are rare in temperate climates like our mid-Atlantic states, appearing more commonly in tropical areas. But spring is a time when we see one of our local native ephemerals spreading out in broad colonies in the woods or on their edges like so many little umbrellas. Podophyllum peltatum, commonly known as mayapple, spreads via rhizomes and sends up stems that usually attach directly to the center of its lobed leaves.

Peltate leaves of annual Tropaeolum majus (garden nasturtium). Photo courtesy of the National Park Service

Other plants with peltate leaves that grow in our climate zones include Tropaeolum (nasturtium), a genus with some 50 to 80 species that originated in South America. In our region, we see it mostly as an annual with leaves up to 4 inches and boldly colorful blossoms, often used to brighten sunny gardens (where it can serve as a summer ground cover, in borders, and, with some varieties, in hanging containers). There are also perennials in the genus. In warmer climates, nasturtiums can bloom year round.

The leaves of our annual garden nasturtiums, Tropaeolum majus, are attached to a petiole in the center of the lower surface. Each 5-petaled flower produces a 3-segmented fruit, each portion with a single edible seed, which when pickled is sometimes called the poor man’s caper. The flowers and leaves are also edible, with a lightly peppery flavor, not unlike cress, and can be used in salads. Their large seeds make them easy to plant, hence ideal for use in children’s gardens.

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Growers of house plants may recognize two plants of tropical origin with peltate leaves: Peperomia polybotrya (raindrop plant), native to Colombia and Peru, and Caladium bicolor (angel wings), widely available in our area for summer foliage color, but not winter hardy. Caladiums can have either lance- or heart-shaped leaves, with veins radiating from the peltate petiole attachment point. Caladiums were first found in the Amazon region. Many other tropical plants are peltate and some, with 6-foot wide umbrella leaves, are grown in greenhouses or conservatories in cooler climates.

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Lotuses and water lilies are also plants with impressive peltate leaves that can easily be seen in our area at Kenilworth Park & Aquatic Gardens in the southeast quadrant of Washington, DC. The garden displays hardy native as well as tropical varieties of both the lotuses (Nelumbonaceae) and water lilies (Nymphaeaceae). The lotus leaves can both float and rise above the water, while the lily pads of many sizes and varieties–but always with a cleft–tend to float atop the water from their long petioles. The circular leaves of native Nymphaea odorata (white water-lily) are bright green above and reddish below with a V-shaped notch almost to the center where the stalks attach. The leaves of the giant Victoria amazonica (Amazon water lily) reach sizes of 6–8 feet in diameter and reputedly are strong enough to hold weights up to 65 pounds or so. They are protected from underwater predators by sharp spines below.

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The word peltate first appeared in the mid-18th Century and stems from the Latin pelta, “armed with a light shield,” ultimately derived from the Greek pelte. In the days when warriors were deflecting swords and lances, they held their shields, often round, but in medieval times evolving toward what has become known as “shield shaped,” with poles or handles attached in the center of the side held toward their bodies.

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