How to identify native and non-native seedlings popping up in the high desert this summer
Text and photos by Madena Asbell, Director of Plant Conservation Programs, Mojave Desert Land Trust
If you live in the high desert, you have probably noticed the landscape has become unusually green recently.
Monsoonal rains across the Mojave Desert this summer have led to the germination of summer annuals like chinchweed and fringed amaranth in some parts of the desert. Summer precipitation in the desert can be spotty and unpredictable, with storm cells delivering a lot of moisture in brief, isolated patches.
Many of these summer forbs provide important forage for desert tortoise and native bees. In addition to annuals, we are seeing a late bloom of many spring flowering shrubs such as paperbag bush, creosote, and desert senna. Here is a brief guide to what you might see now and over the next few weeks, both native and non-native.
Native summer annuals
Chinchweed, Pectis papposa
A small summer annual in the sunflower family with linear leaves and bright yellow flowers. Foliage is aromatic. A favored summer forage plant of the desert tortoise.
Fringed amaranth, Amaranthus fimbriatus
An erect summer annual in the amaranth family. Size varies depending on available moisture, with plants ranging from 6 inches to 3 feet high with many lateral branches. Clusters of small pink to white flowers are borne at the tops of branches. A favored summer forage plant of the desert tortoise.
Slender spiderling, Boerhavia triquetra
A sprawling summer annual with slender stems terminating in small pink flowers. Often found growing within a nurse plant, but also grows in undisturbed open spaces. Other species include B. wrightii, B. coccinea, B. coulteri, and B. diffusa (non-native).
California caltrop, Kallstroemia californica
A sprawling summer annual with rounded opposite leaves and small yellow flowers. Easily mistaken for puncture vine (aka goat’s head), California caltrop lacks the spiked fruits of its non-native cousin. Leaves of caltrop may be slightly more grey-green than those of puncture vine, but the surest way to tell the difference is by looking at the fruits.
Rattlesnake weed, Euphorbia albomarginata
A mat-forming summer annual in the spurge family with small, rounded leaves and even smaller, white-margined (albo=white, marginata=margin) flowers. According to some sources, its common name derives from its use as a folk medicine to treat rattlesnake bites, although its effectiveness has not been proven. Like many other members of the spurge family, rattlesnake weed secretes a milky sap that is toxic to humans. It is a favored forage plant of the desert tortoise. Other species occurring now: E. micromera (Sonoran sandmat).
Six weeks grama, Bouteloua barbata
A short-lived warm season annual bunchgrass native to desert scrub and grasslands from California east to Oklahoma and south to Oaxaca, Mexico. In California it is found from creosote bush scrub to pinyon-juniper woodland in both the Colorado and east Mojave Deserts. It forms low tufted clumps after heavy summer precipitation. Also present now is native needle grama, Bouteloua aristidoides, which has narrower, more numerous seedheads on each stem.
Russian thistle or tumbleweed, Salsola tragus
An invasive annual that grows quickly into a large, rounded bush during summer months. Dead bushes break loose and are blown across the landscape, becoming fuel for wildfire. It’s best if seedlings can be removed when still small, before they become prickly and difficult to remove.
Puncture vine or goat’s head, Tribulus terrestris
An invasive sprawling annual with spiky burrs that can cause injury to people and pets. Easily mistaken for native California caltrop which lacks burrs, look for the spiny fruits before removing.
Millet, Panicum miliaceum
Millet is becoming a more common invasive in the Morongo Basin and in Joshua Tree National Park due to residential bird feeders. To limit the spread of millet into natural ecosystems, seed can be sterilized by baking in an oven for 10 minutes at 140 degrees F.
Native perennial seedlings to look for now:
Desert senna, Senna armata
Desert senna is a grey-green shrub with wavy upright branches that are leafless most of the year. Leaves of young seedlings are hairy and needle-like with small, round lobes. Mature plants typically bloom in spring with profuse displays of fragrant yellow flowers.
Coyote melon, Cucurbita palmata
A sprawling perennial with broad rough leaves, large yellow-orange flowers, and softball-size gourds. Plants are dormant during winter and spring. Leaves and stems emerge and grow quickly in summer from an underground tuber. Seeds germinate after summer rains.
Catclaw, Senegalia greggii
A thorny desert shrub to small tree. Individual or clusters of seedlings germinate from caches stored by rodents or buried by flooding.
Blue palo verde, Parkinsonia florida
A native tree known for its green photosynthetic bark and yellow flowers. Seedlings are stout, blue-green and thorny. Seedling leaves have 2–4 pairs of leaflets. Native to the Colorado and Sonoran Deserts where it grows in and near washes.
Non-native, invasive perennial seedlings to remove:
Jerusalem thorn, Parkinsonia aculeata
A non-native tree related to our native blue palo verde (Parkinsonia florida) that can become invasive in and near washes. Seedlings are distinguished from blue palo verde by their longer leaves and more numerous leaflets.
Native perennials blooming now: creosote (Larrea tridentata), Acton encelia (Encelia actoni), beavertail cactus (Opuntia basilaris), desert senna (Senna armata), paperbag bush (Scutellaria mexicana), Utah vine milkweed (Funastrum utahense), Parish’s goldeneye (Bahiopsis parishii), big galleta grass (Hilaria rigida), coyote melon (Cucurbita palmata), desert croton (Croton californicus), desert willow (Chilopsis linearis), white bursage (Ambrosia dumosa), desert trumpet (Eriogonum inflatum), white rhatany (Krameria bicolor).
For tips on identifying winter and spring annuals, take a look at our guide.
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