Thursday, June 5, 2014

Bear Grass, Yucca filamentosa

After a brief visit with some suburban yuccas yesterday, we thought we'd share a few photos of the native Sandhills bear grass of our youth, Yucca filamentosa. The individuals pictured here are located in the yard of my childhood home and have lived in this spot as long as I can remember. 

The dozens of dangling, bell-shaped flowers are very similar to the yucca blossoms we visited yesterday, and they're every bit as beautiful in the full sun as they were at sunset in our prior post. 

One of the common names for this yucca is Christmas bells, an image readily evoked by the abundant, waxy ivory-colored blossoms.

The numerous curly fibers emerging from the leaf edges are the source of this yucca's scientific name, and an apt name it is. According to the USDA plant guide entry for Yucca filamentosa, the fibers in these leaves are the strongest fibers native to North America, and as long as humans have been around, they've put these fibers to practical use. Stories abound from many sources of historical and current use of yucca fibers by Native American Indians in myriad applications.

More recently, Francis Peyre Porcher cites the virtues of bear grass fiber in his book of 1863, Resources of the Southern Fields and Forests, Medical, Economical and Agricultural: Being Also a Medical Botany of the Confederate States: with Practical Information on the Useful Properties of the Trees, Plants and Shrubs; noting that, "The fibre is uncommonly strong, and is used for various purposes on our plantations: for making thongs for hanging up the heaviest hams, bacon, etc. " 

Porcher goes on to quote an article from the Charleston Courier in July, 1862, entitled Confederate Flax which boasts of "...cordage and twine of different sizes made from the very common plant familiarly know as bear-grass or Adam's needles."

In still more recent times, our eastern North Carolina connections recall stories of yucca leaves' association with the herring fishery, and its superior qualifications as a means of bundling the catch in preparation for drying.

Our friend the leaffooted bug has found these yuccas as well, and it and its kin are in evidence on stems, blossoms and buds, apparently intent on feeding wherever tender plant tissue can be found. The flattened leg segments and white wing markings are even more evident in the bright light of midday.

The closed form and downward orientation of the yucca blossoms is fairly unique in the world of flowering plants, and has yielded one of the most commonly cited examples of co-evolution and symbiotic relationships in the natural world. In fact, Hunter found a question in his biology exam review packet tonight regarding the yucca moth, Tegeticula yuccasella and its amazing relationship with the yucca plant.

According to our Audubon Society Field Guide to North American Insects and Spiders, so dependent are yucca species on the yucca moth for fertilization, that in areas where the moth is absent, no reproduction by seed can occur, and reproduction is by root offshoots only. 

This remarkable story of mutualism begins when an adult female yucca moth forms a sticky ball from the pollen of a yucca flower and carries it to a flower on another plant. She lays her eggs around the ovules (where the seeds will form) of the new flower, then deposits her ball of pollen in a specially formed and perfectly placed "socket" on the flower's stigma, virtually ensuring successful pollination and formation of mature seeds. She then moves on to repeat the process with other flowers. 

When the eggs hatch, the caterpillars feast on the mature yucca seeds, then drop to the ground and pupate until the following year, when they will emerge as adult moths and repeat the cycle...

Segueing from moths back to true bugs, a closer inspection reveals abundant evidence of feeding by the leaffooted bugs on the petal surfaces of the blossoms themselves, some perpetrated while they were still buds, perhaps...

Thanks for joining us in this little excursion down memory lane, and we hope you shared our delight in discovering so many interesting facts about our old friend bear grass and its relatives.

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