Biological Flora of the British Isles: Crataegus laevigata

Abstract

This account presents information on all aspects of the biology of Crataegus laevigata (Poir.) DC (Midland hawthorn) (C. oxyacanthoides Thuill.) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. Crataegus laevigata is primarily a shade‐tolerant shrub or small tree up to 12‐m tall of ancient woodlands (of which it is an indicator plant) and occasionally old hedges, usually on heavy clay soils and avoiding limestone and chalk. It is native to central and northern Europe and in the British Isles is native to southeast England, occurring naturally up to the Midlands, hence the common name. It is largely absent naturally from Scotland, Wales and Ireland. Flowers usually have two styles, varying from (rarely) 1 to 5 with an equal number of pyrenes in the fruit, differentiating it from C. monogyna with usually one style and pyrene. Pollination is by insects and fruit are dispersed primarily by birds. Fruit has traditionally been used for food, and with the leaves and flowers have a long tradition in herbal medicine. Disturbance and fragmentation have allowed C. monogyna to permeate into old woodlands and hybridise with C. laevigata. These two species are inter‐fertile and barriers to hybridisation are primarily spatial separation thus allowing extensive introgression such that in many parts of Europe, pure C. laevigata is becoming scarce.

Biological Flora of the British Isles: Crataegus monogyna

“…Its sister taxon, Crataegus laevigata (cf. Thomas et al, 2021), is scarce in the suite with Quercus robur and is restricted to long-established stands. Another shrubby constant in W8 is Corylus avellana, which is rivalled by C. monogyna only in the Hedera helix and the Geranium robertianum subcommunities.…”

“…Leaf thickness increased with irradiance too, so that leaf mass per area tended asymptotically to 10.12 mg/cm 2 (Aranda et al, 2004), leading towards significant gain in total dry weight (Grubb et al, 1996;Williams & Buxton, 1989 Aranda et al (2004) found hawthorn to be the most shade-intolerant among Ilex aquifolium, F. sylvatica, Quercus petraea, Q. pyrenaica, Prunus avium, Sorbus aria and S. aucuparia. Bradshaw (1948) noted a more tree-like habit in shaded localities compared to C. laevigata (see also Thomas et al, 2021). The Ellenberg value for light (L) is 6 (Hill et al, 1999) indicating the growth of C. monogyna in partially shaded (rarely <20% daylight) to lit places.…”

“…Scutellospora armeniaca Błaszkowski was reported as a fungal partner of arbuscular mycorrhiza with C. monogyna in Poland (Błaszkowski, 1992). Recently Tedersoo (2019, 2020) have questioned the mycorrhizal research conducted over 50 years ago for misinterpretation and consider that the genus Crataegus forms arbuscular mycorrhiza only (see also Thomas et al, 2021).…”

“…In the British Isles, Crataegus monogyna hybridizes most notably with the other native species, C. laevigata, (Thomas et al, 2021). However, in its natural range and where it has been introduced, C. monogyna hybridizes freely with other Crataegus species.…”

Flowering Phenology May Shape Hybridization Patterns of Hawthorn (Crataegus L.) Species

“…Data about flowering phenology in European Crataegus species are scarce, and most studies include only C. monogyna [19], providing little detail about the length and dynamics of flowering in other Crataegus species and no data about their natural hybrids is available [10,32]. The aim of our study was to compare the flowering phenology of three sympatric Crataegus species (C. laevigata (Poir.)…”