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Scientific:
Leptogium rivulare (Ach.) Mont.
French:
Leptoge des terrains inondés
Status:
Threatened
Description:
When dry, a small (up to 6 cm (2 in) across) grey or bluish-grey foliose
(leafy) lichen, speckled with small, reddish-brown apothecia
(spore-producing structures). When wet, the lobes swell, becoming
gelatinous and translucent, giving rise to its common name.
Distribution:
Reported from only 8 locations in North America, 5 of which are in
Ontario. One historic report (1946) from the Lake Temagami area.
Habitat:
Typically found on the bark of trees growing around the edge of
seasonally-flooded woodland pools. Appears to prefer black ash trees but
also may be found on red ash, red maple, silver maple, American elm, bur
oak, balsam poplar, willow, or white cedar trees. Appears to prefer
rough bark on older trees although shrubs are occasionally used as a
substrate. Rarely found on bare weathered wood of dead trees. Grows in
both relatively open and shaded conditions.
Life History:
Grows below the high water mark on trees subject to seasonal flooding.
Location may reduce competition with other arboreal lichens. Most growth
occurs during the period of inundation. However, alternating periods of
immersion and exposure to air appear critical to survival. Reproduction
is by spores (presumably dispersed through water) that are produced in
apothecia and by fragmentation.
Similar species:
The very common blue jellyskin (Leptogium
cyanescens) is larger and lacks the abundant apothecia of this
species. Few species of foliose lichens grow on the substrates occupied
by this species (see below).
Threats:
Limited to seasonally-inundated habitats. Activities that remove trees
supporting the species or modify the hydrologic regime are potential
threats. Because of its apparent preference for ash trees, spread of the
introduced emerald ash borer could have a dramatic effect on this
species.
What you can do: Report
to the Natural Heritage Information Centre: http://nhic.mnr.gov.on.ca/nhic_.cfm.
Avoid activities that would remove trees or change the hydrological
regime in its habitat.
Compiled by: Brian Naylor OMNR |
