May
Because native plants evolved in our recalcitrant climate, they thrive if planted in preferred conditions. Another benefit is the wildlife that certain species can bring to your yard. The kingdom of the Monarch caterpillar and butterfly, for example, is the lowly milkweed.
Wisconsin boasts several native species of milkweed, including the Prairie Milkweed (Asclepias sullivantii), the Dwarf Milkweed (Asclepias ovalifolia), the Purple Milkweed (Asclepias purpurascens), and the profligate Common Milkweed (Asclepias syriaca). The milkweed’s chubby stems, shiny leaves, discs of small flowers—and especially its warty seed pods and parachute-like seeds—are familiar sights in sunny, uncultivated areas across our state. Personal contact with a milkweed reveals the fragrance of its flowers and the sticky milk that oozes from its fractures. That milk is toxic, and it bestows not only the milkweed’s name but also the survival mechanism of the Monarch.
Monarchs evolved with immunity to the milkweed’s poison. As a butterfly, the Monarch lays its eggs on milkweed plants. Growing caterpillars eats leaves containing the toxic milk, making them poisonous to most predators. The resulting butterfly is also poisonous. Throughout its lifecycle, the Monarch needs the milkweed like a summer rose needs the sun and rain.
To invite Common Milkweed to your landscape, pick a sunny, semi-dry spot where it can spread freely. Otherwise, by way of underground shoots, milkweed can quickly elbow aside other ornamentals. Some consider it invasive. Milkweed is easily cultivated by seed or rhizome. Many nurseries have seeds and plants; successful plants usually bloom in the second year.
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