Alfalfa Dodder Cuscuta approximata
Alfalfa Dodder is an introduced annual vine, found in Canada and the lower 48 states. It blooms Jun – Aug.
More about this plant
Cuscuta approximata is a species of dodder known by the common name alfalfa dodder. It is native to Eurasia and Africa, but it is also found in North America, where it is an introduced species and uncommon noxious weed. It is a parasitic vine which climbs other plants and takes nutrition directly from them via a haustorium. The dodder resembles a pile of light yellow to orange-red straw wrapped tightly around its host plant. It is mostly stem; the leaves are reduced to scales on the stem's surface, since they are not needed for photosynthesis while the dodder is obtaining nutrients from its host. It bears clusters of tiny yellowish bell-shaped flowers which are only about 3 millimeters wide. The dodder reproduces by seed, with each plant capable of producing over 10,000 seeds at once. This plant is a weed of alfalfa, clover, and tomatoes, as well as other crop plants and native flora. This species is sometimes treated as a subspecies of Cuscuta epithymum. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 4 derived from its U.S. range
- Lifespan
- Annual
- Foliage
- Broadleaf
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~2 caterpillar species
Cuscuta 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.
Recorded feeding on Cuscuta in North America, including:
✦ Bees specialist-bee host
Specialist native bees depend on it.
Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Cuscuta is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
Related plants
More Cuscuta →
How we know this (2) Methods & honest limits
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 (18) 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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