

Desert Madwort Alyssum desertorum
Desert Madwort is an introduced annual herb, found in Canada and the lower 48 states. It grows to 0.3 ft and blooms May – Jun.
More about this plant
Alyssum desertorum is a species of flowering plant in the family Brassicaceae known by the common name desert madwort. It is native to Europe, North Africa and Asia, and it is found in parts of western North America as an introduced species and sometimes a weed. This is a hairy annual herb producing upright stems up to about 20 centimeters tall. The leaves are linear to oblanceolate-linear in shape, 0.5-4 millimeters long and 0.3-3 millimeters wide. The entire plant is covered by 8-20 rayed stellate trichomes, giving the plant a grayish appearance. It produces small yellowish flowers with petals that are 2-2.5 millimeters long and round, notched fruits 2.5-4.5 millimeters long. The brown seeds are winged, arranged two to a locule, and are about 1.5 millimeters long. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 4 derived from its U.S. range
- Height
- 0.3 ft
- Lifespan
- Annual
- Foliage
- Broadleaf
- Flower colour
- Yellow AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~2 caterpillar species
Alyssum supports ~2 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a modest genus for introduced plants — native genera typically support far more.
Recorded feeding on Alyssum in North America, including:
How we know this (3) Methods & honest limits
We read each species’ measured specific leaf area (leaf area per unit dry weight) from the Global Spectrum dataset and band it: thin & fast (high SLA), medium, or thick & tough (low SLA). The global median is about 10 mm²/mg.
Honest limits: A species-mean from pooled measurements — individual plants vary with light and site. A broad strategy signal, not a precise per-plant figure.
A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (19) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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