Medicago sativa

Supported alfalfa identification

Record the character combination supporting identification, alternatives considered and evidence still missing.

1. Do leaflet margins, flower arrangement and mature pod form jointly support Medicago sativa over clovers, black medic or another Medicago? definition
2. Which photographs, specimen or expert determination support the identification, and were reproductive structures available? provenance

Documented biological material

Distinguish verified cultivar information from inferred traits and leave unresolved taxonomic assignments explicit.

1. What seed-lot or breeding record supports the cultivar name, dormancy rating, resistance claims or declared engineered traits? provenance
2. Does the chosen taxonomic authority include the observed falcata-associated or hybrid material within Medicago sativa, and how should uncertainty remain attached to this registry entry? boundary

Establishment success and reseeding context

Record emergence and mortality while retaining competition and potential autotoxicity as separate explanations for poor reseeding. [Alfalfa reseeding discussion](https://ucanr.edu/blog/sjc-and-delta-field-crops/article/alfalfa-qa-notes-field)

1. What proportion of the sown viable seed produced surviving seedlings, and how does survival vary across the sampled area? measurement
2. When was alfalfa last present, do old plants or decomposing crowns remain, and what local evidence is needed before reseeding? action

Root and symbiosis evidence

Record root extent, branching, lesions and nodule observations with the excavation method and limits of diagnosis.

1. What root depth or sampled root extent, branching pattern and nodule distribution are actually observed? measurement
2. What evidence supports effective nodulation, and what further assessment would distinguish ineffective nodules, root galls and other root abnormalities? definition

Recovery after defoliation

Record maturity, regrowth and cutting history when assessing harvest-persistence tradeoffs; avoid treating canopy height as a direct measurement of root reserves. [Harvest and regrowth guidance](https://blog-crop-news.extension.umn.edu/2022/05/managing-risk-at-first-alfalfa-harvest.html)

1. How many days have elapsed since the last defoliation, and what stem height, developmental stage and new-shoot distribution are observed? measurement
2. Does the stand's recovery and locally supported seasonal guidance justify another cut, grazing event or additional rest? action

Persistent live stand

Combine live crown counts, stem production, root inspection and cultivar context before assigning decline or mortality.

1. How have live crown density, stems per crown and the proportion of injured crowns changed between comparable surveys? measurement
2. What observations distinguish dormancy or delayed regrowth from irreversible crown death in this cultivar and climate? definition

Supported stress attribution

Retain competing explanations until plant observations and site measurements justify a causal assessment.

1. Which measured root-zone conditions and weather events coincide with wilting, yellowing, restricted roots or failed regrowth? measurement
2. What additional soil, tissue or root assessment would change the decision to irrigate, amend nutrition or defer intervention? action

Diagnosis-linked intervention

Require organism identification and relevant sampling before selecting an intervention, with linked checks for harvest intervals and pollinator effects. [UC alfalfa IPM guidance](https://ipm.ucanr.edu/agriculture/alfalfa/integrated-pest-management/)

1. What evidence distinguishes alfalfa weevil feeding, aphid injury, crown or root disease and non-biological damage in this stand? definition
2. Which locally validated threshold, crop stage and forage-versus-seed objective support intervention, and what harvest or pollinator constraints apply? action

Purpose-specific harvest readiness

Record the evidence for harvest timing and transfer the identity and condition of removed material to the relevant forage-product model.

1. What dry-matter yield, maturity distribution, leaf retention and measured forage composition support the intended harvest? measurement
2. Which observations must accompany harvested or grazed material into forage and livestock models before suitability for a particular animal group is decided? boundary

Effective reproduction and movement

Distinguish flower presence from viable seed and record neighbouring flowering alfalfa when assessing pollen-mediated trait movement. [Alfalfa coexistence guidance](https://ucanr.edu/blog/uc-weed-science-weed-control-management-ecology-and-minutia/article/co-existence-rr-and)

1. What pollinator activity, pod set, filled-seed counts and germination results demonstrate successful reproduction? measurement
2. Given neighbouring flowering alfalfa and observed volunteers, should flowering be retained for seed, interrupted or followed by recruitment monitoring? action

Kinds and varieties

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Medicago sativa subsp. sativa (purple-flowered cultivated alfalfa)
• Medicago sativa subsp. falcata (yellow-flowered, cold-hardy sickle lucerne)
• Medicago sativa nothosubsp. varia (sativa × falcata hybrid; variegated flowers)
• Fall-dormancy classes FD 1-11 (the practical agronomic grouping of cultivars)
• Hay-type vs grazing-type (or grazing-tolerant) cultivars
• Flemish / northern European types vs Mediterranean / non-dormant types
• Glyphosate-tolerant (Roundup Ready) transgenic cultivars vs conventional cultivars
• Landraces and wild or semi-wild populations versus certified named cultivars

1. Which of these kinds and varieties hold for the sense of Medicago sativa this model covers, and on what evidence? provenance

Identifiers and schemes

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Wikidata - Q156106 - Item for the species Medicago sativa.
• ITIS TSN - 183623 - Integrated Taxonomic Information System taxonomic serial number.
• USDA PLANTS symbol - MESA - Standard plants-database symbol for Medicago sativa L.
• IPNI / POWO LSID - urn:lsid:ipni.org:names:506308-1 - Linnaean name Medicago sativa L.; Kew POWO accepted taxon.
• NCBI Taxonomy - 3879 - NCBI taxid for Medicago sativa.
• GRIN taxon id - 23690 - USDA-ARS Germplasm Resources Information Network.
• EPPO code - MEDSA - EPPO Global Database code used in plant health.
• HS / CN - 1214.10 (lucerne/alfalfa meal and pellets); 1214.90 (other, including hay) - WCO Harmonized System headings for traded forage products, not the living plant.

1. Which of these identifiers and schemes hold for the sense of Medicago sativa this model covers, and on what evidence? provenance

Standards and regulation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• ISTA International Rules for Seed Testing - International Seed Testing Association (purity, germination, other-seed counts for lucerne/alfalfa seed lots)
• AOSA Rules for Testing Seeds - Association of Official Seed Analysts (North American official seed testing of alfalfa)
• OECD Seed Schemes (Grass and Legume Seed) - Organisation for Economic Co-operation and Development ( varietal identity and certification of Medicago sativa in international seed trade)
• UPOV Test Guidelines TG/6/5 Medicago sativa L. - International Union for the Protection of New Varieties of Plants (DUS examination for plant-variety protection)
• Federal Seed Act and state certified-seed rules - USDA Agricultural Marketing Service and U.S. state seed-certifying agencies (labeling, noxious-weed seed, germination claims)
• Directive 66/401/EEC (fodder-plant seed marketing), as retained or recast nationally - European Union / member-state seed authorities (marketing of certified lucerne seed)
• APHIS biotechnology regulation of glyphosate-tolerant alfalfa events (e.g. J101, J163) - USDA Animal and Plant Health Inspection Service
• Feed hygiene and contaminant limits for alfalfa hay, meal and pellets (mycotoxins, pesticide residues, undesirable substances) - Codex Alimentarius; EU undesirable-substances in feed (Directive 2002/32/EC); national feed-control bodies

1. Which of these standards and regulation hold for the sense of Medicago sativa this model covers, and on what evidence? provenance

Real-world use

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Primary perennial hay and silage crop in temperate dairy and beef systems (cut 3-8+ times per year depending on climate and dormancy class).
• Grazed pasture or mixed grass-legume swards, including stockpiled autumn grazing in some regions.
• Dehydrated meal, cubes and pellets sold as a high-protein, high-calcium feed ingredient, including to horses and as a dairy concentrate extender.
• Nitrogen-fixing rotation or cover crop that leaves residual N for following cereals; also used as green manure when ploughed in.
• Sprouted seed sold as a salad vegetable (alfalfa sprouts); seed is a distinct food-safety pathway from forage.
• Honey plant: extrafloral and floral nectar supporting commercial alfalfa-leafcutter-bee (Megachile rotundata) seed production in western North America.
• Germplasm and breeding: public and private cultivar development for fall dormancy, disease resistance, grazing tolerance and, in some markets, herbicide tolerance.
• Exported as compressed hay and pellets from the western United States, Canada, Australia and Spain into East Asian livestock markets.

1. Which of these real-world use hold for the sense of Medicago sativa this model covers, and on what evidence? provenance

Typical measurements

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Crude protein in well-made vegetative hay - 16-22 (exceptionally 14-25) - % of dry matter
• Neutral detergent fibre (NDF) of hay at mid-bud to early bloom - 38-48 - % of dry matter
• Fall dormancy rating of commercial cultivars - 1-11 - dimensionless class (NAAIC standard tests)
• Seeding rate (drilled, pure stand) - 8-20 (typically 12-18 in humid regions; lower in arid irrigated stands) - kg ha⁻¹
• Taproot depth of established plants - 2-5 (occasionally deeper on unrestricted soils) - m
• Seed germination (certified seed, laboratory) - 80-95 (hard seed often 5-20 of the remainder) - %
• Dry-matter yield of irrigated temperate stands - 8-20 - t ha⁻¹ year⁻¹
• Chromosome number of cultivated alfalfa - 2n = 4x = 32 - chromosomes

1. Which of these typical measurements hold for the sense of Medicago sativa this model covers, and on what evidence? provenance

Failure modes and hazards

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Autotoxicity and poor autogenic reseeding: established stands suppress new alfalfa seedlings, so rotation out of alfalfa is usually required before re-establishment.
• Winterkill and ice-sheet injury in low-dormancy cultivars grown too far north; conversely, overly dormant cultivars yield poorly in long-season climates.
• Crown and root diseases (Phytophthora root rot, Aphanomyces, anthracnose, Verticillium wilt, Fusarium, bacterial wilt) that thin stands after 3-6 years.
• Insect damage: alfalfa weevil (Hypera postica), potato leafhopper (Empoasca fabae) causing hopperburn, aphids, and in some regions clover root curculio.
• Bloat (frothy ruminal tympany) when hungry ruminants graze lush pure-stand alfalfa, especially in vegetative growth.
• Sprout-associated human foodborne illness (Salmonella, E. coli, Listeria) from seed that cannot be fully surface-sterilised; several national outbreaks have been traced to alfalfa sprouts.
• Photosensitisation and, rarely, cantharidin poisoning when blister beetles (Epicauta spp.) are conserved in crimped hay and fed to horses.
• Adventitious presence of transgenic (glyphosate-tolerant) seed in conventional or organic lots, which has triggered export rejections and coexistence disputes.
• Mycotoxins and heating/mould in poorly cured hay; dust and respirable particles causing farmer's lung (extrinsic allergic alveolitis) in hay handlers.

1. Which of these failure modes and hazards hold for the sense of Medicago sativa this model covers, and on what evidence? provenance

Regional variation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• English common name is alfalfa in North America and much of Latin America (Spanish alfalfa), and lucerne in the United Kingdom, Ireland, Australia, New Zealand, South Africa and much of non-Romance Europe.
• Fall-dormancy classification (FD 1-11) is the North American commercial language; Europe more often speaks in terms of Mediterranean vs Flemish/northern types and winter-hardiness scores.
• Seed production is concentrated in arid irrigated districts (Pacific Northwest, California, Idaho; also Canada, Australia, France, Argentina) even when the forage is grown in humid dairy regions.
• China, the United States, Argentina and the EU are large forage producers; Japan, Korea and the Arabian Peninsula are major importers of compressed hay rather than local growers.
• Subsp. falcata and hybrid varia material is agronomically important in continental and boreal climates (Russia, northern Plains, Scandinavia, Inner Asia) and is often invisible in Mediterranean seed catalogues.
• Organic and export-to-China/Japan markets treat adventitious GMO presence as a hard barrier; those constraints barely exist in some purely domestic feed markets.
• Sprout consumption as a ready-to-eat vegetable is common in North America and parts of Europe and East Asia, and is almost absent as a use-class in regions that know the plant only as fodder.

1. Which of these regional variation hold for the sense of Medicago sativa this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Medicago falcata (sickle medic; often treated as M. sativa subsp. falcata) - Yellow (not purple) flowers, sickle-shaped rather than coiled pods, typically diploid, and greater cold hardiness; flower colour and pod coiling separate field plants, while chromosome count and molecular markers separate breeding material.
• Medicago × varia (hybrid lucerne / sand lucerne) - Variegated or mixed purple-yellow flowers and intermediate pod shape; treated as the sativa × falcata hybrid (nothosubsp. varia). Flower-colour mix in a stand is the field test; pedigree or marker data is the breeding test.
• Medicago lupulina (black medic) - Annual or short-lived, much smaller plants, yellow flowers, and black coiled pods; a lawn and roadside weed, not a hay crop. Size, life cycle and pod colour separate it at a glance.
• Medicago polymorpha and other annual medics (burr medic, barrel medic) - Winter-annual medics of Mediterranean and southern-Australian ley farming, with spiny burrs that contaminate wool; distinguished from alfalfa by annual habit, yellow flowers, and spiny pods.
• Trifolium pratense (red clover) - Another perennial forage legume cut for hay, but with palmate trifoliolate leaflets lacking alfalfa's serrate tip, sessile pink flower heads, and a shallower root system. Leaflet shape and inflorescence separate them in the field; hay can be told by leaf and flower remnants and by a typically lower protein and different isoflavone profile.
• Melilotus officinalis / M. albus (yellow and white sweetclover) - Taller, more branched biennials with elongate racemes of small yellow or white flowers and a strong coumarin (new-mown-hay) odour; sweetclover hay can cause dicoumarol bleeding in livestock if spoiled. Odour, inflorescence shape and biennial habit separate them from alfalfa.
• Onobrychis viciifolia (sainfoin) - Non-bloating perennial forage with pinnate (not trifoliolate) leaves and dense pink spike inflorescences; used where bloat risk or calcareous soils make alfalfa a poor choice. Leaf dissection and inflorescence are decisive.
• Medicago truncatula (barrel medic) - A diploid annual model species in genomics, not a perennial hay crop; distinguished by annual habit, coiled spiny pods, and NCBI/community use as the model rather than the crop. Do not treat genome papers on M. truncatula as if they described cultivated alfalfa.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of Medicago sativa this model covers, and on what evidence? provenance