Desert Vegetation Slideshow

1. The slideshow included slides of both vegetation and landscapes of the four North American deserts.
2. The Mojave Desert was featured prominently with photos of: creosote bush (Larrea tridentata), bursage (Ambrosia dumosa), 4-wing saltbush (Atriplex canescens), shadscale (Atriplex confertifolia), desert holly (Atriplex hymenelytra), snakeweed (Gutierrezia sarothrae), globe mallow (Sphaeralcea ambigua), brittle bush (Encelia farinosa), the 3 Mojave yuccas – the Mojave yucca (Y. schidigera), the banana yucca (Y. baccata), and the Joshua tree (Y. brevifolia). We also saw the century plant (Agave utahensis), the gymnosperm, Mormon tea (Ephedra viridis), some of the desert annuals, including the desert marigold (Baileya multiradiata), and the cacti – barrel cactus (Ferocactus acanthodes), hedgehog (Echinocereus engelmannii), old man cactus (Opuntia erinacea), the beavertail (Opuntia basilaris), buckthorn (Opuntia acanthhocarpa), riparian plants, plants found on sand dunes, in oases, and an endangered plant of the Mojave Desert, the bear-paw poppy, Arctemecon californica..
3. With these plants in mind, we discussed evergreen shrubs (creosote bush), drought-deciduous plants (bursage, brittle bush), the absence of arborescent plants in the Mojave Desert (like the saguaro cactus), the plethora of annuals, especially winter annuals, CAM pathway of succulents, salt tolerance in some plants, such as the Atriplex grouping.
4. We looked at the transition zone at the northern end of the Mojave, which included a plant community type in transition between the Mojave Desert to the south and the Great Basin Desert to the north. The community type was the blackbrush community (Coleogyne ramosissima).
5. The Great Basin Desert was dominated by sagebrush (Artemisia tridentata) on the bajadas, and shadscale (Atriplex confertifolia) and other shrubs in the lower elevations. Some of those shrubs included rabbitbrush (Chrysothamnus nauseosus).
6. In the higher elevations within the Great Basin Desert (and the Mojave) we saw elements of the P-J community (Pinyon pine –Juniper), with Pinus monophylla and Juniperus osteosperma.
7. We also saw slides of Great Basin riparian areas with its more fully developed riparian zones. We saw more complex profiles of plant canopies which included cottonwoods (Populus spp.), willows (Salix spp.), tall shrubs, sub-shrubs, and ground cover.
8. For the Sonoran Desert we saw the sub-tropical influence with presence of stem-succulent plants, such as the saguaro cactus (Carnegia giganteus), the huge cardons (Pachycereus sp.), and the old man cactus (Lophocereus schottii). We also saw palo verde in the washes (Cercidium floridum), and the ironwood, (Olnyea tesota)..
9. On the Sonoran bajadas, there were the drought-deciduous ocotillos (Fouquiera splendens).
10. In the oases, the California palms (Washingtonia filifera).
11. We saw only a few slides of the easternmost North American desert, the Chihuahuan, with one of its signature plants, the century plant, Agave lechugilla.
12. This was followed by a series of slides representing a brief botanical review of parts of plants we had discussed earlier in the semester.

The emphasis here is not on the individual plants, but rather the relationship of the plant type with the characteristics of each of the 4 deserts. For example:

1. What types of annuals would you expect to be dominant in the Mojave?, the Sonoran?, the Chihuahuan?

2. What is an evergreen plant?

3. What is a drought-deciduous plant?

4. Why are riparian areas not as well-developed in the Mojave Desert as they are in the Sonoran Desert?

5. Why are there few representatives of arborescent plants in the Mojave Desert?

6. Why are there stem-succulent plants in the Sonoran Desert, but none, or few, in the Mojave Desert?

7. Why does saltbush, but not creosote, colonize the dry lake beds (playas) of the lower elevation Mojave Desert?