One of the bad things about being trained in ecology is that sometimes it gets in the way of our enjoyment of the world around us. That's especially true when it comes to our mixed feelings about non- native plants that on one hand are extremely pleasing to the eye but on the other are doing their darndest to crowd out native species. For example, Japanese Honeysuckle--Lonicera japonica--makes a little flower with an intoxicatingly pleasant odor, but the vine itself can strangle the living daylights out of good-sized saplings. At Hilton Pond Center we've made moderate progress in exterminating honeysuckle, but now the lovely Periwinkle--both Vinca major and Vinca minor, brought over long ago from Europe--have crept in and carpeted parts of the property so thickly that nothing else can grow. Fortunately, not all foreign invaders are quite as aggressive, and we have come to almost tolerate a little herbaceous plant called Asiatic Dayflower.

All text & photos © Hilton Pond Center

Dayflowers--as their name suggests--bear ephemeral blossoms attractive to bees and other smaller pollinators that have to work quickly, since in sunny weather the flowers open in early morning and disintegrate into a jelly-like mass by noon. Blooms last a bit longer in cooler, cloudy weather. Classified in the Spiderwort Family (Commelinaceae), dayflowers have a worldwide distribution, principally in the tropics. The Asiatic Dayflower, Commelina communis (above), is from east Asia but has invaded almost all of the U.S. except Nevada and the Pacific Northwest. Although it grows weedlike in warmer parts of its adopted range, it is actually cultivated under glass as an ornamental in Europe and cooler parts of North America. There are also three native Carolina species of Commelina, all of which at least superficially resemble Asiatic Dayflower.

The most noticeable attribute of Asiatic Dayflower is two prominent sky-blue petals that stick out like mouse ears (bottom photo); in fact, across parts of its range it is known as "Mouseflower." (In Japan it is referred to as "Monsoon Flower" because it blooms in the rainy season; it is considered to be a major weed in Tokyo.) Actually, all dayflowers have three petals--not two--but one is often much smaller; in Asiatic Dayflower the third petal is the miniscule white structure that hangs beard-like beneath the rest of the blossom. The blooms are produced terminally, at the end of a stem and surrounded by a nearly translucent heart-shaped leaf (top photo). The rest of the three-inch leaves are narrow and pointed, with parallel veins along their length (above right). At this time of year, it's hard to find a leaf that doesn't have at least one hole in it--evidence that caterpillars and other small herbivores have been dining on the foliage.

The entire Asiatic Dayflower plant is almost succulent, with thick and watery three-foot-long stems punctuated by bulbous nodes that produce the leaves and numerous side branches (left). Leaves ensheath the stem. The plant propagates by seed but also colonizes laterally when stem nodes touch the ground and put out roots. Under the right conditions--partial to full sun and above-average moisture--Asiatic Dayflower can grow from a single plant into a yard-square cluster in less than one growing season. It is this "community" growth pattern (below right) that gives rise to the scientific epithet of C. communis. The genus name Commelina recognizes the work of Dutch botanists Johan and Caspar Commelin, brothers represented by the two large blue petals; in a sort of botanical cruelty joke, a third brother who made no scientific contributions is memorialized by the dayflower's insignificant third petal.

A head-on view of Asiatic Dayflower (bottom photo) shows the mouse-ear petals, plus a remarkably complex assortment of reproductive parts on a blossom that is only about an inch square. There are three sterile stamens (the top three yellow structures) and three fertile stamens (the bottom yellow structure and two slightly lateral curved structures bearing flattened brownish ovals). These fertile stamens produce pollen that is transported by bees to the head of a neighboring flower's pistil--the remaining curved structure with the tiny, pinkish tip. When a pollen grain is deposited on the sticky tip of the pistil, it grows down into the ovary and fertilizes an egg. The embryo within the whitish-green ovule grows very rapidly; the photo below left shows two ripening ovules with dead flowers still attached, while a third blue-petalled flower awaits the next day to bloom. Each ovule produces one or two granular eighth-inch reddish seeds that typically germinate the following year after lying dormant in the soil. Asiatic Dayflower is an annual, so regular re-seeding is all-important for survival.

Blossoms of Asiatic Dayflower often glisten in the sun, sometimes from dew but primarily because the petals contain a few unpigmented cells scattered among the many that are blue. These clear cells--nearly bursting with water--reflect the light, adding all the more to the pleasing appearance of this non-native visitor to Hilton Pond Center. Thus far it only grows in the drain field from our septic tank, but we're ready to go after it with the weed-eater if it gets too rambunctious. For now we're content to tolerate--and appreciate--the short-lived blossoms of our bright blue Asiatic Dayflower.

All text & photos © Hilton Pond Center

SPECIES BANDED THIS WEEK:
Ruby-throated Hummingbird--7

* = New species for 2003

OTHER SIGHTINGS OF INTEREST

--Six Ruby-throated Hummingbirds were banded at Hilton Pond Center on 30 Aug. That particular date has been by far the most productive over our 20 years of banding RTHUs, with a total of 72 hummers. The second best date is 4 Aug with 47 RTHUs banded.

A very early young female Rufous Hummingbird (above) was banded on 30 Aug at Indian Land in Lancaster County SC.

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Hilton Pond Center for Piedmont Natural History is a non-profit research & education organization in York, South Carolina USA; phone (803) 684-5852. Directed by Bill Hilton Jr., aka "The Piedmont Naturalist," it is the parent organization for Operation RubyThroat. Contents of this website--including articles and photos--may NOT be duplicated, modified, or used in any way except with the express written permission of Hilton Pond Center. All rights reserved worldwide. To obtain permission for use or for further assistance on accessing this website, contact the Webmaster