Saturday, April 13, 2013

Yellow Jessamine

Beautiful lianas of lemony-yellow flowers are sure to attract the attention of travelers through the Carolinas and elsewhere in the southeast. This plant is the state wildflower of South Carolina: Yellow Jessamine, Gelsemium sempervirens, sometimes known as Carolina Jasmine. I saw it blooming in profusion on my recent trip to South Carolina, and had to stop to make some images.

The largish tubular flowers suggest Trumpet-creeper, Campsis radicans, or to my eye, something in the Figwort Family (Scrophulariaceae). But the plant belongs to the Logania family (Loganiaceae), which is closely allied to the Figwort Family, and the plant does indeed sometimes go by the name "trumpetflower".

Note the long corolla tube, which sits in a cup of pointed pale green sepals. The anthers are held on long filaments, and extend to the summit of the corolla tube. These blossoms are sweetly fragrant, but very poisonous. All parts of the plant are said to be infused with strychnine alkaloids, especially the nectar. Even handling the foliage can allegedly cause minor dermatitis, so it's best to take a hand's-off approach with this plant.

As I moved around taking photos, it didn't take long to realize that large carpenter bees (thanks Randy Mitchell for the ID!) were important pollinators of Yellow Jasmine. The large fuzzy insects were everywhere and rapidly darting from flower to flower.

The bees quickly entered the cuplike flowers and pushed to the base of the blossom where the nectaries, presumably, are located. Their visits were incredibly rapid, however - usually the bee would be in and out of a flower in two seconds or so.

Given the brevity of their visits, I had to wonder if the toxicity of the nectar is something that the bees can only marginally tolerate, and must gather in small doses. Probably not, though, seeing how many visits the animals would make to various flowers. Each bee certainly gathered an impressive amount of nectar (and pollen) over the course of their collective visits.

In order to access the sweet stuff, the bee must dive headfirst deep into the flower. This act forces its fuzzy body into contact with the anthers and pollen, and with its next visit to a flower, it'll rub some of that pollen off on the flower's stigma, thus cross-pollinating the plants.

A perfect fit. It would seem that large bumblebees, carpenter bees and Yellow Jessamine were made for one another, and they probably are. Coevolution of plants and animals is a very cool thing.


zippiknits said...

Lovely photo journal of the Carolina Jasmine and bumblebees.

In California we have a yellow figwort that grows in semi swampy areas along the coast where a small creek comes down to the sea. The flowers remind me of this cousin from the Carolinas.

Randy Mitchell said...

The shiny abdomen and short tongue suggests that this is a carpenter bee, not a bumble bee

Jim McCormac said...

Ah - good catch, Randy. Thank you.