Eucalyptus morrisbyi Image removed, due to copyright morrisbys gum T A S M A N I A N T H R E A T E N E D S P E C I E S L I S T I N G S T A T E M E N T Scientific name: Eucalyptus morrisbyi Brett, Pap. & Proc. Roy. Soc. Tasmania 129: pl. 14–15 (1939) Common name: morrisbys gum Group: vascular plant, dicotyledon, family Myrtaceae Status: Threatened Species Protection Act 1995: endangered Environment Protection and Biodiversity Conservation Act 1999: Endangered Distribution Biogeographic origin: endemic to Tasmania Tasmanian Natural Resource Management Region: South Tasmanian IBRA bioregions (V6): South East Images removed due to copyright Figure 1. Distribution of Eucalyptus morrisbyi, showing Plate 1. Eucalyptus morrisbyi: buds, capsules, adult & IBRA bioregions juvenile leaves (scale bar=2cm) Threatened Species Section – Department of Primary Industries, Parks, Water and Environment Listing Statement for Eucalyptus morrisbyi (morrisbys gum) SUMMARY: Eucalyptus morrisbyi (morrisbys gum) seed. The Calverts Hill stand in particular has a is a small tree endemic to Tasmania’s southeast. large number of seedlings that have been It is only known from two locations 21 km repressed by continuous browsing to ground apart; in the Government Hills near Risdon, level and potentially may be many years old. and the fragmented Cremorne subpopulation Plants in the Risdon stand have resprouted which now consists of a main stand at Calverts from lignotubers following a major dieback Hill and several small remnant stands following event and genetic testing of stems has past clearing for residential and agricultural demonstrated considerable clonality in the purposes. The Risdon and the main Calverts stand (Jones et al. 2005). Hill stands have suffered rapid dramatic declines in recent decades with the loss of all Eucalyptus morrisbyi is susceptible to drought, but a few mature trees which are all located at being the first of the local eucalypts to show Calverts Hill. The Risdon stand is now signs of stress following drought events, with considered to be functionally extinct as it no stress symptoms particularly evident in trees longer produces seed. This leaves the species growing on drier sites. Stressed plants including with fewer than 30 mature trees in the wild that any regrowth are more susceptible to vertebrate produce seed. The species appears to have been and insect browsing, often rapidly resulting in contracting to wetter gullies over time, death or dieback. exacerbated by the recent warmer and drier conditions associated with climate change. The There are considerable genetic differences species is highly palatable and once stressed, between the Calverts Hill and Risdon stands. recovery is hampered by vertebrate and insect Plants from the Risdon stand are less palatable browsing that if left unchecked leads to the to vertebrate browsing as demonstrated in death of trees within years. The smaller mixed plantings (Mann et al. 2012). However, roadside stands in the Cremorne area are plants from the Risdon stand have been shown additionally at risk from clearing to improve to be more susceptible to myrtle rust road safety and the small Lumeah Point stand (Austropuccinia psidii) (newly introduced to cannot expand due to existing urban Tasmania) than those from Calverts Hill (Potts development. While at imminent risk of et al. 2016). Plants from the two stands can be extinction in the wild, the species is not likely to distinguished using molecular techniques (Jones face extinction in the short to medium term due et al. 2005). Some molecular differences are also to ornamental and ex situ plantings. The most evident between plants from the Calverts Hill immediate needs are to protect wild and stand and its associated remnant stands in the planted seedlings at Calverts Hill to allow them Cremorne area. Despite the small size of the to reach maturity and to ensure that the genetic Risdon subpopulation, variation remains high variability of the species is maintained by and it is not showing signs of inbreeding. This supplementing and managing seed collections may be a consequence of inbreeding being that can be used for future conservation limited by the high levels of self-incompatibility actions. shown by the species (Potts & Savva 1988) and the longevity of the existing genotypes. Although Eucalyptus morrisbyi hybridises with IDENTIFICATION AND ECOLOGY Eucalyptus viminalis in the wild, studies have not Eucalyptus morrisbyi is a small tree, growing to a revealed significant contamination of its gene height of approximately 6 to 12 m. Seedlings pool. take about ten years to produce flowers, a relatively long time for eucalypts. Peak Description flowering occurs from February to May While Eucalyptus morrisbyi is generally rough (Williams and Potts 1996). The species is more barked at the base of the trunk, the old bark is or less well adapted to fire, which stimulates shed further up leaving the upper part of the release of seed from capsules for regeneration. trunk and the branches smooth and brown, If flowering is compromised, the canopy held white-grey or pink-grey in colour. The bluish- seedbank is only viable for about two years as green juvenile leaves are glaucous, unstalked capsules become too woody to release their Threatened Species Section – Department of Primary Industries, Parks, Water and Environment 2 Listing Statement for Eucalyptus morrisbyi (morrisbys gum) and rounded, 2 to 3 cm long and 2 to 4 cm prone, low rainfall area. It is associated with wide. They are arranged in opposite pairs. The poor soils, with the Calverts Hill and associated adult leaves are stalked, less glaucous and remnant stands occurring on recent sands arranged alternately. They are about 5 to 10 cm overlying dolerite and the Risdon stand on long and 1.5 to 4 cm wide. The flower buds Permian mudstone. The species tends to occur have a pointed cap and are glaucous and shortly in relatively pure stands with a number of other stalked. They arise in clusters of three from the eucalypt species occurring nearby. leaf axils. The flowers are cream and develop into cylindrical, glaucous, woody capsules, RESERVATION STATUS 9 to 11 mm long and 6 mm wide (Plate 1). Eucalyptus morrisbyi is formally protected in the [description based on Curtis & Morris 1975] Calverts Hill Nature Reserve and the East Risdon State Reserve. The Lumeah Point stand Survey techniques is on a coastal reserve that has been leased to This small tree can be identified at any time of the Clarence City Council for recreational use. the year, though mature trees (with capsules) are required to confirm the identity of this POPULATION PARAMETERS species. Number of subpopulations = 2 (1 reproductive) Number of locations = 2 (1 reproductive) Confusing Species Extent of occurrence ~45 km2 Eucalyptus morrisbyi can be confused with the Area of occupancy ~ 12.5 ha closely related Eucalyptus gunnii (cider gum), and (0.5 ha for mature individuals) Eucalyptus cordata (heart leaved silver gum). It Area of occupancy (as per IUCN criteria) = 8 km2 can be distinguished from Eucalyptus gunnii by (or 4 km2 as reproductive in only 1 location) its coastal lowland habitat and presence of No. of mature individuals < 30 warty protuberances on buds and capsules. It Eucalyptus morrisbyi is known only from two can be distinguished from Eucalyptus cordata by subpopulations in the wild (Table 1). In the its smaller capsules that occur in the axils of Cremorne area, the subpopulation has been adult leaves only. Refer also to Wiltshire and fragmented into the Calverts Hill stand, and Potts (2007). Eucalyptus morrisbyi can hybridise several small remnant stands approximately with Eucalyptus viminalis and some stands and 2 km away. The species is no longer present at older plantings contain a significant proportion some sites where it was collected in the past in of hybrid trees. The hybrids are readily the Cremorne area. Numbers in the smaller distinguished by their narrower and less remnant stands have been supplemented by glaucous juvenile leaves. plantings and other plantings in the area have been made. A census of trees in the Risdon DISTRIBUTION AND HABITAT subpopulation in 1996 showed 69 trees with Eucalyptus morrisbyi is endemic to Tasmania with adult foliage though less than 20 of these were wild occurrences known only from the carrying seed. This stand is now functionally Cremorne area, with a main stand at Calverts extinct with only weak, spindly, non- Hill and several small nearby remnant stands, as reproductive lignotuber regrowth remaining. well as from a small subpopulation 21 km away The Calverts Hill stand is close to being in the Government Hills near Risdon (Figure 1, functionally extinct. There were 1915 mature Table 1). A number of conservation plantings trees in the Calverts Hill stand in 1991 and only have been made and Eucalyptus morrisbyi has seven mature trees were still alive in early 2018 been widely planted as a specimen tree and (one dying) following a dramatic decline that ornamental. started after 2005 (and was first reported in 2014 at which time 70 to 80% of mature trees In natural stands, Eucalyptus morrisbyi occurs in had already died). Seed-bearing mature coastal, dry sclerophyll woodland on gentle to individuals can still be found in the small hilly slopes where it tends to be restricted to remnant patches in the Cremorne area though gullies that offer some relief in this drought Threatened Species Section – Department of Primary Industries, Parks, Water and Environment 3 Listing