Species of the Week
In the Species of the Week feature of the Wildwood Web we took a close look at one of the species that lives in Wildwood. To see the earlier featured species check the Species of the Week archives.
Two species of jewelweed or touch-me-not are found in Wildwood. In fact, both of them grow together at the bottom of the Grand Staircase. Impatiens pallida, pale jewelweed or pale touch-me-not (above), has yellow flowers with a few red-brown spots. Impatiens capensis, spotted jewelweed or spotted touch-me-not, (below) has orange flowers with red to red-brown spots. Both have egg-shaped, toothed leaves, although pale jewelweeds leaves are a bit bigger. Old-fashioned garden impatiens, also called Bizzy-Lizzy, is Impatiens balsamina; although modern cultivated impatiens are mostly hybrids
The species name, pallida, simply means "pale." The species name capensis, though is a bit more interesting. It means "of the Cape" and refers to the Cape of Good Hope at the south end of Africa. As both species are native Americans, it seems odd that spotted jewelweed should be named after a location in Africa. The botanist who named it was under the mistaken impression that it had been imported to European gardens from Africa, rather than from America, and the rules of botanical nomenclature do not allow changing a name merely because it doesn't fit.
Interestingly, the flowers undergo a sex change. When they first open they are male, but later change to female. How can you tell their sex? Look into the opening of the flower. If you see white pollen, it's male. If you see a little green pin, it's female. The green pin is the tip of the female pistil waiting to receive pollen from another plant. A hungry insect visiting a male flower will land on the landing platform formed by the two lower petals, and press inward, seeking the nectar way down inside the spur and getting dusted with pollen. If the same insect later visits a female flower it will brush against the pistil as it squeezes inward in search of nectar, and deposit pollen upon it. Some insects, however, have evolved to rob the poor jewelweed; they chew holes in the spur and suck the nectar out without the bother of pollinating the flower. The showy, nectar-filled flowers we are discussing are formed during the lazy days of summer. Later in the season, with frost approaching and the sunshine reduced, the plant will make small flowers that have no petals or nectar and never open. Instead, these flowers will self-pollinate and produce seeds. These late season flowers are easy to make, in terms of energy needed; however, the more expensive summer flowers have the advantage of increasing genetic variation among the offspring.
Jewelweeds are plants of moist woods, brooksides and seeps. Their stems and leaves are juicy and succulent. On the hotter days of midsummer the plant will wilt from water loss, but will revive when the air cools. Most plants close their stomata, the microscopic openings through which leaves breathe, when they are hot, to prevent water loss. I have heard, though I do not know if it is true, that jewelweeds do not do this preferring, instead, to let the water evaporate, cooling the plant in the same way our sweat cools us. Obviously, only a plant that lives in wet areas can adopt that strategy.
The sap from the plant is supposed to stop the itching of poison ivy. I have never tried this myself, but I've seen it claimed in so many books, I suspect it may be true, at least for some people. I'd be interested to hear from anyone with actual experience with this.
Jewelweeds are in the family Balsaminaceae, the Jewelweed or Touch-me-not Family. There are about 40 species in the family, all but one in the genus Impatiens. Most members of the family live in south Asia, particularly in India, and south Asia is where the cultivated species originated. The two species in Wildwood Park are native to the eastern US and a few more species are found in the western US. Cultivated plants sometimes produce seed that comes back wild the next year, but they are not a weed around here. Tropical countries are another story, and I have seen big patches of weedy garden impatiens spreading deep within the forests of O'ahu and Puerto Rico.
Jewelweeds are annuals. This is hard to believe sometimes, when you come upon a thicket of jewelweeds four or five feet tall. All that grew from seed this year? However, stop by the park after the first frost and you will find all the thickets of jewelweed dying, for they are very frost tender. The seeds they flung out so wildly in the summer are cold-hardy and will wait until next year. In the spring look for the pale green fleshy leaves of young jewelweeds coming up, and know that more jewel-like flowers and explosive seedpods will be found again in mid to late summer.
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