Thursday, July 23, 2015

Daucus carota, the Wild Carrot

Daucus carota
Daucus carota is a species from Europe and western Asia, introduced into several countries including America, probably inadvertently imported with grain seed. The plants are biennial, meaning it they take two to three years to bloom from seed, after which time they will set seed and die. They are similar to the cultivated carrot (Daucus carota subsp. sativus), and have white taproots that smell like carrots, but are typically far too woody to be considered edible unless they are very young and still somewhat tender. The flower cluster, an either flat-topped or domed inflorescence, is composed of hundreds of even smaller umbels of simple five-petaled flowers. Often, a single reddish to maroon colored flower sits in the dead center, speculated to attract pollinators. The plants are variable, growing anywhere from under a foot tall to over four feet. The leaves are fern-like.

Daucus carota panoramic
This year has shown to be just right for the carrots, they have flowered more prolifically than any preceding year that I have lived here, which is around six years. Out of a mix of a lack of available time, laziness, and a touch of curiosity I have left our field unmowed. This has allowed all of the flowering plants that have bloomed thus far to set seed uninterrupted, but as a consequence is also good for hiding pests like ticks (deer frequent the field daily). The panorama does not do it justice, there are a thousand flower umbels just in this scene.

Despite everything I've read in books on the subject, my honeybees are working the wild carrot eagerly, as the photos and the video below will illustrate. I think they are primarily interested in the nectar, but they all seemed to have a small amount of pollen on their legs (this is incidental, a consequence of running all over the flowers, I suspect).

As this video (above) shows, the bees work their way from floret to floret until they feel satisfied with their harvest from that particular umbel.

It is common to see multiple foragers on a single umbel. Above we can clearly see a honeybee in the foreground, and a black solitary bee in the upper left (and in the photo below).

Solitary bee
Many small solitary bees can be found on Daucus. While the honeybees may just be capitalizing on the great abundance of carrot flowers and perhaps a relative lack of another plentiful resource, small solitary bees are common and usual visitors of the tiny flowers. They often have short proboscises (the bee tongue) so the shallow, easily accessible florets of Daucus are just right for them. 

Many many flies visit these flowers, some shown in previous posts. Flies are usually short tongued insects, so they tend to visit plants with shallow florets. Most of the plants in the Apiaceae (parsley family, included carrots) have shallow florets. Flies are beneficial in this way, and in agriculture are used in place of honeybees to pollinate carrot fields for production of seed.

Ladybug and ants
Often regarded as "beneficial bug" attracters, offering a food source for short tongued "good bugs" like lady beetles, lacewings, and other insects that prey of garden pests.

Mating beetles
These beetles are sometimes found feeding on the flowers (more commonly, on the Madia), but these two have decided to mate. I have mentioned before, flowers are a common place for many species of beetles to mate and find mates.

Pompilid wasp
Wasps of all types are some of the most common visitors to the carrot flowers. Pompilid wasps are an interesting group of solitary wasps, chiefly because they hunt spiders. I once saw one drag away a wolf spider twice its size! The spiders, sometimes kept alive but paralyzed, are used to feed the wasp's young.

Ichneumon wasp
Despite looking dangerous, these wasps are probably harmless... to human. To insects, they are terrifying creatures. The "stinger" is actually an ovipositor (think of the movie 'Alien') which is used to lay eggs. Some species lay their eggs inside of, on, or near a host which will serve as a food source for the larvae, of course in a state of paralysis. This type of lifecycle was the inspiration for the lifecycle of the aliens in the 'Alien' movies.
Polistes dominula
This wasp is an invasive species, known as European paper wasps. They build paper like nests in the eves of houses and within piles of rubbish. The nests have an open and visible cell structure, hexagonal paper cells facing the ground. The nests of paper wasps look similar to those of the native wasps, for instance yellowjackets (Vespula), except that the European paper wasp nests are open while nests of yellowjackets are closed with a single opening towards the bottom.

Polistes dominula
Paper wasps have a characteristic style of flying, their hind legs extend and hang out and down while in flight. They are among one of the many species of wasp that are usually present at barbecues, the reason being they collect meat and other insects to feed their young. Their main prey are caterpillars, which they chew up and regurgitate to feed their larvae.

Polistes dominula
Despite their carnivorous nature, adult wasps feed primarily on nectar of plants like carrot with shallow florets and easily accessible nectar. While they lack the hairiness of bees, they do act as pollinators for many plants by transferring pollen, just not very efficiently.

Hornet (left) and yellowjacket (right)
Two native wasps that will easily be mistaken for the European paper wasp are shown above. The differences are most apparent in their markings, similar but different. Other differences are there but would require a dead specimen and a hand lens to decipher them. Hornets are considered ground dwellers while yellowjackets nest in trees (or eves) like the European paper wasps.

Daucus carota earns one of it's names, bird's nest, when it sets seed. The entire inflorescence curves in on itself, suggesting the shape of a bird's nest, as shown below. Seed is set, distributed by birds (I think) or mechanically, and the process starts anew.

I'll leave you with some questions: How much time shall pass before an ecosystem restores balance after the introduction of an alien species? It has happened before, animals, natural events (floods, wind, the ice ages, etc.), and even indigenous peoples around the world have contributed to the spread of plant species. When does "nonnative" become "native"? The questions aren't posed to defend the spread of nonnatives, but rather to contemplate the world around oneself. Peculiar, life.

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