Yellow Hairgrass Aira praecox
Yellow Hairgrass is an introduced annual grass, found in Canada and the lower 48 states. It grows to 0.3 ft and blooms May – Jul.
More about this plant
Aira praecox is a species of grass known by several common names, including early hair-grass, yellow hairgrass and spike hairgrass. It is native to Europe, where it is found in dry, sandy places, on rocky outcrops, and in heath grassland. It also grows in North America as an introduced species, where it can be found on the east and west coasts in sandy or rocky areas, such as beaches and roadsides. This is a tuft-forming annual grass growing up to about 10 to 15 centimeters in maximum height. The thin, narrow leaves are located at the base of the stem, and are typically 0.3–2 millimeters wide. It bears small, tightly congested inflorescences of purple-tinted green bisexual spikelets. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 7 derived from its U.S. range
- Height
- 0.3 ft
- Lifespan
- Annual
- Foliage
- Broadleaf
Wildlife & pollinators
How pollinator value is scored →Wildlife & visitors 2 birds
Open records of who else uses Yellow Hairgrass — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 2 birds species (fruit, seed, browse):
Related plants
More Aira →
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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