Current understanding of the Poa annua life cycle

Abstract

Poa annua L. is a common component of turfgrass systems both as a weed and a desirable species. Since first classified by Carl von Linné in 1753, nearly 50 taxa of P. annua have been described, with delineations made on the basis of plant morphology and not life cycle. Yet, peer‐reviewed turfgrass literature has recognized only two of these taxa over the past 50 yr, P. annua L. var. annua and P. annua var. reptans, categorizing var. annua ecotypes as upright growing annuals and var. reptans ecotypes as laterally growing perennials. Herein we provide a comprehensive review of peer‐reviewed literature to highlight that these associations between life cycle and plant morphology are flawed given that morphology is plastic and strongly influenced by environment. We conclude by exploring knowledge gaps regarding P. annua perennation that, if addressed through research, would help turfgrass managers better understand the biology of the ecotypes they aim to eradicate or maintain.

Mesotrione and Amicarbazone Tank-mixtures for Annual Bluegrass (Poa annua) Control in Cool-season Turfgrass

“…T. Koyama or upright habit (i.e., bunch-type growth habit, no stoloniferous growth) characteristic of P. annua subsp. erecta (Carroll et al, 2021). y Visual estimate of mean annual bluegrass cover in the nontreated plots on a 0% (no cover) to 100% (complete annual bluegrass cover) scale in April or May and in midsummer (late July or August).…”

“…A lack of heat, drought, and disease tolerance compared with other cultivated turfgrass species makes it difficult to manage and thus it is often considered a weed (Beard et al, 1978). Annual bluegrass often behaves as a perennial, particularly where cool-season turfgrasses are intensively managed, and preemergence herbicides are not an effective control option (Carroll et al, 2021;Reicher et al, 2017).…”

Poa annua: An annual species?

“…(wheat) and Zea mays L. (maize) are annuals that senesce after fruiting regardless of environmental surroundings [4,5]. Despite its name meaning annual in Latin, P. annua does not Although the nature of P. annua transience in some situations remains uncertain, review of literature indicates the species may be incorrectly botanically characterized [60]. If any environmental factors are causing plant death rather than programmed senescence after inflorescence production, classification as an annual species does not follow the accepted definition of such a life cycle [3].…”

Modeling seasonal emergence of Poa annua in urban greenspace

“…Poa annua (annual bluegrass) is the most troublesome weed of managed turfgrass in urban greenspaces 4 . Having been documented on all continents including Antarctica 5 , P. annua is highly adaptable and noted for having ecotypes varying in morphological characteristics 6 . A day-neutral flowering plant 7 , P. annua seed germination has been studied in growth chamber environments with ecotypes germinating independent of daylight and across an air temperature range of 10 to 39 °C 8 .…”

“…Ecosystem services provided by urban greenspaces are continually threatened by P. annua given that the species produces upwards of 100,000 seeds per square meter 18 – 20 . There is also widespread evidence that once established, P. annua can persist perennially 6 . There is a need to better understand environmental conditions triggering seedling emergence patterns to assist turfgrass managers with optimally timing interventions—both chemical and non-chemical—for P. annua control.…”