By ROBERT DRYJA
Los Alamos

Small canyons can provide a variety of microenvironments that are close to one another. A small stream along the bottom of a canyon provides a moisture laden environment. But the adjacent canyon sides can be much dryer just 10 feet up.

Sections of the stream may have small ponds with water skippers on their surfaces. But the stream may be without water in between the ponds. The water from the ponds has percolated down into the stream bottom rather flowing from one pond to the next.

Coyote willow and mullein are two plants that use different strategies for survival even though their microenvironments are similar. Both can be found growing along dry stream beds. Coyote willow grows in thickets. A thicket may be twenty to thirty feet in length with dozens of narrow, upright straight stems growing close together. The leaves on the stems are narrow, about a quarter of inch wide and a few inches long. 

Mullein in contrast grows as single plants that may be at a considerable distance from one another. A mullein has a few leaves compared to a coyote willow. However, these leaves are huge. A single leaf may be twelve inches long and four inches wide. The surface of a mullein leaf feels fuzzy while the surface of coyote willow leaf is smooth.

Two survival strategies are at work. One strategy focuses on surviving in an occasionally flooded stream. The other strategy focuses on absorbing as much available light as is possible for growth. A few coyote willow plants are more likely to survive as part of a spread-out thicket when flooding occurs. In contrast, a single mullein by itself may be washed away or buried in silt when flooding occurs.

The second strategy is in response to the shadiness of a canyon bottom. A mullein with its large leaves absorbs most of any sunlight available at the plant. A single narrow leaf of a coyote willow does not receive much sunlight in comparison. A multitude of leaves along a stem helps compensate but a lot of sunlight still passes between the leaves.   

Something remarkable can happen for three or four days in the early summer. The air near a thicket of coyote willow fills with cotton-like whisps. These whisps are so small and light that they drift along even when there is no apparent breeze. The wisps are carrying very small seeds from the coyote willow and provide a way to widely disburse them.

Coyote willows grow a type of seed pod called a catkin. It is a few inches long. It can be described as a caterpillar covered with yellow spikes. It is initially covered with what looks like cotton. The yellow coloration appears when the cottony surface blows away, carrying mature seeds. The survival strategy is to disburse seeds widely so that some may land in favorable growing conditions.  

A catkin shows a yellow seed spike with silky cotton covering one end. Photo by Robert Dryja 

Mullein is remarkable in its own way, although not as visually dramatic. Mullein lives for two years. A single vertical stalk grows in its second year. This stalk is surrounded with flowers that grow capsules.  Each capsule may contain several hundred seeds. The combined total number of seeds may be in the range of 100,000 to 200,000. The seeds do not disburse widely but the environment close to a parent plant may be favorable for growth. Only one seed out of the thousands needs to successfully grow in order for a mullein to survive from generation to generation. 

A mullein displays large leaves that grow in a circle around the single, central stem. Photo by Robert Dryja