Poa angustifolia

Poa angustifolia was first described by Carl Linnaeus in Species Plantarum (1753: 67).

The name is typified by material in Linnaeus’s herbarium (UPS). A lectotype has been designated from Linnaean collections.^[3]

• 1753 — Linnaeus described P. angustifolia as a distinct species in Species Plantarum.^[4]
• 1831 — Du Mortier listed P. angustifolia with its own diagnosis, but within his framework he subordinated it under Poa pratensis as a subspecies.^[5]
• 1890s — Rouy treated the P. angustifolia as P. pratensis proles angustifolia, reflecting its close affinity with the P. pratensis complex. In his Flore de France, he distinguished two forms: the “common” or typical form, and the "bristle-like form. ^[6]
• Early 20th century — Numerous forms (forma) were described by Soó, Podpěra, Domin, and others, emphasizing morphological variation in leaf width and panicle structure.
• Mid 20th century — Some floras considered it conspecific with P. pratensis, while others retained it as a narrow‑leaved segregate.^[7]
• Present — Modern databases accept P. angustifolia L. as a distinct species, though many regional floras still treat it as a subspecies or variety of P. pratensis.^[8][9][10]

In the protologue, Linnaeus cited several earlier works that described similar grasses:

• Bauhin, Pinax Theatri Botanici (1623), vol. 2, proar. 5 — an early systematic compilation of plant names.
• Scheuchzer, Agrostographia (1719) — one of the first dedicated grass monographs. Scheuchzer gave a full morphological account of the narrow‑leaved meadow‑grass. His description was later echoed by Linnaeus in separating P. angustifolia from the broader‑leaved P. pratensis.^[11]
• Flora Lapponica (1737) — Linnaeus’s Lapland flora, where he described awl‑leaved forms and noted their abundance across Lapland, intermixed with related species.^[12]
• Flora Svecica (1745) — Linnaeus’s own account of Swedish flora. Linnaeus did not name P. angustifoolia in the description but emphasized the narrow leaves and the open panicle, distinguishing it from P. pratensis (Kentucky bluegrass or common meadow-grass), which has broader leaves and a denser panicle.^[13]
• Flora Parisiensis (1749) — was a regional flora of the Paris basin that incorporated diagnostic notes on grasses. In this section, the author Dalibard, described a meadow‑grass with ovate‑oblong spikelets and awl‑shaped leaves. This narrow‑leaved form corresponds to what Linnaeus later formalized as P. angustifolia in Species Plantarum (1753). Linnaeus cited Dalibard’s wording directly in the protologue, using it as corroborating evidence to separate the taxon from the broader‑leaved complex of P. pratensis.^[14]

These references demonstrate how Linnaeus anchored his new species concept in the broader European botanical tradition.

P. angustifolia has an extensive synonymy, reflecting its variable morphology and shifting taxonomic concepts. The following names have been published as synonyms of P. angustifolia L.^[15][16][17]