Tomentose

Day 108: Botanical word for the day: tomentose, i.e., a covering of fine, woolly hairs. It derives from Latin "tomentum" which, to my great amusement, means "cushion stuffing," although today's cushions are largely stuffed with polyurethane foam. What advantages would there be for a plant to have evolved tomentose foliage? Several, as it turns out, the first being that the woolly surface is more difficult for insects to navigate and thus they tend to avoid tomentose leaves. The matted hairs of the tomentum (here used in the non-cushion sense) also insulate tender surface cells from frost and wind. They also reduce the rate of transpiration and reflect harsh sunlight. Harking back to an earlier point in this discussion, an article in a recent issue of Scientific American suggests that plants which have more textured leaf surfaces are affected by fewer insect pests. Scientists monitored the difficulties beetles had in traversing leaves with various microscopic surface structures and found that they took longer to cross a given distance on a textured leaf than on a smooth-surfaced one.

Nesting Nidula

Day 59: One day I returned a little late to the office after a lunchtime walk and was explaining to Kevin that I had been sidetracked by a specimen of Hemitomes congestum while searching for Drosera rotundifolia, blathering on about the uniqueness of the find and the proliferation of mycoheterotrophic species I had been observing through the months of spring, only to have him say, "Crow, I have no idea what you're talking about." It pulled me up short and made me see that while I was throwing around botanical names and terms as casually as if I had been talking about Fred and George, most people are a bit uncomfortable with scientific jargon. I realize now that it might be easier on my readers if I provided a glossary, so let me give you one to accompany this photo of one of my favourite fungi, Nidula niveotomentosa, aka "Bird's-Nest Fungus."

Very often, the Latin name of a species will tell you something about its characteristics. In this case, "-tomentosa" refers to the presence of a tomentum, a velvety or woolly texture found on the surface of a plant. The view through the microscope at the top left shows this attribute...a fuzzy-wuzzy nest for the "eggs" which give this family of fungi its common name. The "eggs" (shown in the nest in the center 'scope view) are called peridioles. These contain spores. The bottom 'scope view shows the peridioles liberated from the "cup," appropriately called a peridium.

On the right, you can see the Bird's-Nests in situ alongside a flourishing colony of Peltigera membranacea, a member of the family of Pelt lichens. The translucent structures which appear like stalactites on the underside of the "leaf" are rhizines, a root-like structure which attaches the lichen to its substrate of rock, wood or soil. If you think fungus-jive is hard to wrap your tongue around, lichen terminology is another breed of cat. We'll get to that in future posts.