Often you will notice a powdery white coating on raspberry and blackberry stems, as well as on a variety of fruits, including plums, blueberries, grapes and apples, and on the leaves of plants as well. This outer layer is referred to as bloom, and is produced by the plant’s epidermal cells. It consists particles of cutin, a waxy, water-repellent substance, embedded in epicuticular wax. One of its main functions is to reduce the loss of water. In repelling water, bloom also prevents bacteria and mold spores as well as air pollutants from entering the plant. In addition, it is responsible for the self-cleaning mechanism of plants. Bloom prevents dirt and other particles from sticking to the plant, so that when water rolls off the plant, it takes the dirt away. Using biomimicry, scientists have developed paint and textiles that stay clean by repelling dirt and water. Bloom is routinely harvested to polish and protect cars and furniture.
Thank you so much for all of your warm, welcoming emails regarding my first and only grandchild. Naturally Curious blog posts may be intermittent for the next week or so, but eventually will resume five posts a week.
Fringed Polygala looks a bit like a miniature orchid, but it is not — it is in the Milkwort family. The structure of its ¾-inch bright magenta-pink blossoms is well-suited for its bumblebee pollinators. The bee lands on the pink fringe at the front of the flower and its weight triggers the white “keel” to drop down. A slit at the keel’s top opens, exposing the reproductive parts of the flower. Pollen from the stamens is rubbed onto the bee’s hairs while it probes deeply into the base of the flower for nectar, while pollen from a previously visited Fringed Polygala is scraped off onto the stigma, where it needs to be in order for fertilization to take place.
The combination of Bottle Gentian’s (Gentiana clausa) blossoms’ brilliant purple/blue color, their shape, and the difficulty insects have in prying open the bottle neck their petals form, make them a highlight of every September. Getting inside their flowers is a monumental task, and one that few insects, other than fairly large species of bumblebees, attempt — much less accomplish. It takes several seconds of pushing, shoving and cramming to get their head through the miniscule opening at the top of the blossom. Eventually their body follows, sliding down into the flower. While the whole bee sometimes disappears, it’s more usual to see their hind legs poking out of the flower while they lap up nectar. Not only are bumblebees strong, but their tongues (see insert) are long enough to reach the copious amount of sugar-laden nectar that awaits them inside the flower.
As with Pink and Yellow Lady’s Slippers, one of Showy Lady’s Slipper’s three petals is greatly modified into a large inflated pouch called the labellum. The two other petals attract pollinators with an alluring odor, but the insects that enter into this pouch are in for a disappointment, as lady’s slippers produce little or no nectar. Once inside, visiting insects are guided by very fine, slanting hairs on the inner surface of the pouch towards the flower’s pistil and stamens. Once it has entered the constricted passageway that leads to the reproductive parts, an insect cannot turn around and must pass by the pistil and stamens. Lady’s slippers rarely self-pollinate, so it is crucial that they not only attract, but also extract pollen from insects to achieve cross-pollination. Thanks to their structure, this happens more often than not. The flowering of Showy Lady’s Slippers peaks in Mid-June in central Vermont; if you know of a nearby fen (peat wetland that gets its water from rainfall and surface water), best visit it soon, as that’s where you’re most likely to find this species of orchid.
Pitcher plant leaves are primarily green in the summer, tinged with red, but as summer turns into fall, many become deep red. Although this red color was thought to attract insects, it appears that this is not the case. The color change, according to research cited in the Journal of Ecology, is due to the level of phosphorus this carnivorous plant has received from its insect meals. There is a limited amount of phosphorus in a bog and plants living there acquire it in different ways. The pitcher plant acquires phosphorus from insects that it traps. It then utilizes the phosphorus to revitalize the (green) chlorophyll in its leaves for photosynthesis. The deep red color that the leaves turn in the fall indicates that the plant has not had a good meal in quite some time.
Poison Ivy is in the Anacardiaceae family, which also includes cashews, mangos and sumacs. The sap of the stems, roots, fruit and leaves of many species in this family contains urushiol oil, which is what causes the allergic rash in 80% of humans that come in contact with these species. Poison Ivy is very sensitive to carbon dioxide, and even slightly elevated levels of CO2 have proven to increase its growth. In the past 50 or 60 years, during which time the amount of carbon dioxide in the atmosphere has increased by roughly 22%, Poison Ivy’s growth rate has doubled. The amount of urushiol oil has not only increased, but it is also more potent…leaves of three, let them be.