

Ferngrass Catapodium rigidum
Ferngrass is an introduced annual grass, found in the lower 48 states. It grows to 0.3 ft and blooms Apr – Jun.
More about this plant
Catapodium rigidum, ferngrass, is a species of annual grass in the family Poaceae, distributed around the Mediterranean and the Middle East. It has been widely introduced throughout drier parts of the world, including parts of North America, South America, South Africa, Korea, Australia, and New Zealand. Individuals can reach 20 cm (8 in). Wikipedia →
Ferngrass is flagged invasive in the U.S. These natives fill a similar niche — same growth habit, bloom season, height, and region — so you keep the look and feed local wildlife instead of spreading a problem.
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 5 derived from its U.S. range
- Height
- 0.3 ft
- Lifespan
- Annual
- Foliage
- Broadleaf
Wildlife & pollinators
How pollinator value is scored →Wildlife & visitors 53 birds
Open records of who else uses Ferngrass — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 53 birds species (fruit, seed, browse) — the most-recorded:
How we know this (4) 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.
We place each species on Grime’s competitor–stress-tolerator–ruderal (C–S–R) triangle using the globally-calibrated “StrateFy” method: leaf size drives the competitor score, dense low-area leaves the stress-tolerator score, and thin high-area leaves the ruderal score. The result is a C/S/R percentage mix and one of 19 strategy classes; we show it in plain words and keep the percentages for the curious.
Honest limits: A species-mean strategy from pooled global leaf measurements — a broad ecological signal, not a precise per-plant or per-site value. Derived, never a measured fact.
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.
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
Sources for this entry (20) 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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