slideshow included slides of both vegetation and landscapes of
the four North American deserts.
- The Mojave
Desert was featured prominently with photos of: creosote bush
dumosa), 4-wing saltbush (Atriplex canescens),
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..
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.
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
to the north. The community type was the blackbrush
community (Coleogyne ramosissima).
- The Great
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).
- 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.
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.
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)..
- On the
Sonoran bajadas, there
were the drought-deciduous ocotillos (Fouquiera splendens).
- In the
oases, the California palms
- 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.
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:
What types of annuals would you expect to be dominant
in the Mojave?, the Sonoran?,
What is an evergreen plant?
What is a drought-deciduous plant?
Why are riparian areas not as well-developed in the Mojave
Desert as they are in the Sonoran Desert?
Why are there few representatives of arborescent plants in the Mojave Desert?
Why are there stem-succulent plants in the Sonoran Desert,
but none, or few, in the Mojave Desert?
Why does saltbush, but not creosote, colonize the dry
lake beds (playas) of the lower elevation Mojave Desert?