By David Moll
People seem to really like Wright’s Silktassel. They seem to like it primarily because it’s an evergreen shrub, its broad, leathery leaves lending rich green color to winter landscapes. It also happens to be a useful illustration of botanical phenomena.
That attractive foliage is a clear example of plants that have leaves paired opposite one another on the branch. Other plants have an alternating or a whorled leaf arrangement. Furthermore, Wright’s Silktassel’s opposite leaves are set at horizontal right angles from the leaves at the preceding and following nodes. The fancy name for this phenomenon is decussation and leaf arrangements exhibiting it are called decussate. This is the most common formation among vascular plants. Leaf arrangement is a good thing to notice in our botanical explorations.
Wright’s Silktassel is also an example of plants that have boy flowers and girl flowers on separate plants. This opens the topic of plant sexuality and can help us understand what we’re seeing when we investigate the plants we find in the field. We may be most familiar with flowers that have boys (stamens) and girls (pistils) on the same flower, but boys and girls can be on separate flowers, separate plants, or some mix. Let’s not forget vegetative reproduction which begs the evolutionary question of why sex at all.
If fertilized, those girl flowers will mature into a dark blue, berrylike fruit. Birds, such as the exquisite songster the Hermit Thrush, consume these fruits and subsequently disperse the seeds. This broaches the topics of coevolution, symbiosis and ecology. It’s interesting to note that while silktassel seeds can be dispersed by animals, its flowers are wind-pollinated.
It’s not a dominant plant, occurring only here and there, but in a wide range of elevation and habitat types. It’s found mostly in our Interior Chaparral, and trending up into Pinyon-Juniper and Ponderosa Pine.
As mentioned at the outset, people seem to like this plant even if they don’t know what it is; but then they find out what it is and want some for their yard. Many native plants are apparently not practical for nurseries to grow, but, when questioned about it, Steve Miller, owner of The Native Garden had this to say: “It’s readily available and transplants easily. We always have it in stock.”
So, from principals of evolution to symbiosis to native landscaping, Wright’s Silktassel is an outstanding plant.
David Moll studies nature in Arizona.