Hypochoeris Radicata L. (Achyrophorus Radicatus (L.) Scop.)

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Section: Hypochoeris. Herbaceous perennial growing from hard, thickened, overwintering base (caudex); fibrous-rooted, but often with several enlarged roots, and appearing tap-rooted; leaves in a basal rosette, hispid with simple hairs, oblanceolate, toothed or pinnatifid, 3-25 cm long and 0.5-7 cm wide; stems 15-60 cm tall, usually several from each rosette, erect or ascending, usually forking, enlarged below the heads and bearing many small scale-like bracts, possessing a 'milky' latex; capitula 20-30(-40) mm wide, usually 6-9, terminating the branches; florets yellow, ligulate monoclinous and bisexual, the ligules surpassing the involucre and about 4 times as long as wide, the outer ones greenish or grey-violet beneath; involucre 18-25 mm high at anthesis, cylindricalcampanulate, up to about 25 mm in fruit, its bracts imbricate, dull green, glabrous or hispid; fruit an achene (Fig. 2(d)), orange or brown, body of the achene usually 4-7 mm long, from a little longer to more often much shorter than the slender beak, the prominent nerves and the lower part of the beak muricate; pappus plumose with two rows of hairs, those in outer row shorter and commonly merely barbellate.Considerable variability has been reported for H. radicata. European workers have recognized several subspecies, varieties and forms (Hegi Fl. ed.

Assembly of nonnative floras along elevational gradients explained by directional ecological filtering

“…restricted to warmer conditions at low elevation and others (e.g., Hypochaeris radicata, Plantago lanceolata, and Rumex acetosella) capable of establishing viable populations at the highest elevations. Independent data show that this latter group is largely composed of species with broad climatic amplitudes (28,(30)(31)(32). As a result, the nonnative floras of higher elevations are composed of nested sets of species with increasingly wide elevational amplitudes, a process we call directional ecological filtering.…”

Phylogeography of the invasive weed Hypochaeris radicata (Asteraceae): from Moroccan origin to worldwide introduced populations

“…As Turkington & Aarssen (1983) commented with respect to the occurrence of H. radicata in Great Britain, it is very difficult to establish what are native populations for such a successful invasive species. We hypothesize that, on the basis of our results, the heterocarpic ancestral populations of H. radicata expanded out of northern Africa via a series of stepping stones across the Strait of Gibraltar area into the southern Iberian Peninsula in the Quaternary.…”

“…Hypochaeris radicata is a very successful colonizing species that now has a presence on virtually all continents. Beyond its probable native area in the Mediterranean region, where it occurs in relatively sparse populations associated with humid evergreen woodland, H. radicata is a successful invasive weed in Northern and Central Europe, where it is apparently very flexible with regard to soil requirements and growth conditions (Turkington & Aarssen 1983), and recent studies in southeastern Australia showed that H. radicata is one the most common dicotyledonous plants of temperate perennial pastures (Dellow et al 2002). Likewise, Doi et al (2006) found H. radicata in all parts of temperate Japan, commonly in grasslands, with a distribution that is still expanding, and this species is also very common in South America (Cabrera 1971(Cabrera , 1978(Cabrera , 1987 with populations comprising large numbers of individuals.…”

Fresh “Pollen Adhesive” Weakens Humidity-Dependent Pollen Adhesion

“…We focused on the exposure time on an hourly time scale because the opening and presentation of a flower of H. radicata lasts for 3–7 h, and the pollen transport by pollinators is likely to be completed within a day.…”

“…We also have plotted typical results of f a transitions from consecutive force measurements of fresh and aged pollen grains under fluctuating relative humidity (RH) (Figure 2c,d). We focused on the exposure time on an hourly time scale because the opening and presentation of a flower of H. radicata lasts for 3−7 h, 23 and the pollen transport by pollinators is likely to be completed within a day.…”