Plant story - safeguarding yellow eyebright, a highly threatened plant species

Introducing yellow eyebright (Euphrasia scabra)

Family - Scrophulariaceae

Common name: yellow eyebright

As with other species of eyebright,  yellow eyebright (Euphrasia scabra) it is a root hemi-parasite that is largely dependent on surrounding plants for its nutrition. It was reputably once common in the cooler area of New South Wales, Victoria, Tasmania, South Australia and Western Australia, but has undergone a dramatic decline in the last 100 or more years.

The threats facing yellow eyebright

There are thought to be several contributing factors for the decline of yellow eyebright, predominantly habitat loss through clearance for agriculture and housing, weed invasion and also inappropriate management regimes, including fire and grazing pressures. One other factor that is considered a serious threat to the remaining populations is climate change. Lack of spring rains, unseasonable floods, and droughts affect this species heavily year to year due to its life cycle and habitat in flat marshy area. Its conservation status throughout its former range is as follows:

• The species went for 100 years without any records being made in New South Wales until three small populations were found in close proximity in 1999. The total population for the state is estimated as fluctuating between 250 and 500 individuals. It has had its listing in this state elevated from Extinct to Endangered.
• In Western Australia this plant species is listed as a Priority Two, meaning that not enough information is known about it for a meaningful assessment. It is currently known from four small populations.
• In South Australia it is considered extinct with no suitable habitat remaining.
• In the Victoria region, Euphrasia scabra was widely collected in the 19th century, however the species has declined dramatically and is now known from seven populations, only three of these regularly support more than a few hundred individuals. It is listed as Endangered in the state.
• In Tasmania the species was also widely collected in the 19th century. After extensive surveying in the late 1990’s, only six populations were located with a further 11 populations now considered to be most likely extinct. Only one of these six populations regularly supports more than 200 individuals. The species is listed as Endangered in the state.

A taxonomic review of the species

In addition to this, recent work is indicating that there needs to be a taxonomic review of this species as there appears to be more than one taxon currently included under this name.

Collecting seeds

In Tasmania seed was collected from this species at the beginning of March 2007 after three months of monitoring. The population at Dukes Marsh in the Tasmanian Eastern Tiers is by far the largest in the state fluctuating between approximately 200 and 2,000 individuals year to year. Anecdotal reports suggest that seed can persist in the soil seed bank for some time and that germination is dependent on the timing and intensity of seasonal rains and/or cold spells. However, the germination cues have not been explored to date.

In the 2007 season, an unusually dry spring resulted in the marsh being totally dry with only a very scattered early germination of 50-100 plants noted in early January. Some light rains in the middle of that month produced a second flush of germination with approximately 250 plants present at the end of the month. Throughout February, the Marsh dried out again and many of the plants commenced flowering as poorly developed single stems.

At the time of ripening of the first third of the fruit (the species flowers from the base of a long spike-like raceme, and is usually still flowering when the lower fruits are mature), heavy rains brought flooding and inundated much of the Marsh to knee depth. This inundated approximately 80% of the population washing away mature seed. It is not known whether this species can survive inundation; a quick wade at the time revealed that many plants were still looking quite healthy despite being under 60cm of fast flowing water. Some searching in the higher parts of the Marsh revealed approximately 80 individuals that were free of the water (as well as a healthy harvest of large leaches that had migrated up to avoid the water and lay in wait for the warm blood of a seed collector!). Seed was carefully collected from 25 individuals, which produced on cleaning an impressive ~7500 seeds, indicating seed production is certainly not a limiting factor for this species.

The conserving of a parasite may not immediately strike people as important. However, recent studies on the impact of Rhinanthus minor (Bardgett et al. 2006 Nature. Vol. 439: 969-972.) show that annual parasitic plants can play an important role in maintaining species diversity within habitats through differential growth suppression effects and enhanced soil nutrient recycling.

Tasmania currently has ten species of eyebright incorporating at least 22 distinct taxa, 19 of which are endemic and 13 of which are listed as Threatened. The vulnerability of these unusual and iconic plants has prompted the Department of Primary Industries and Water to develop a post to oversee and research their conservation along with its native orchids.

The Euphrasia scabra collection represents SeedSafe's 6th eyebright collection and its 5th Euphrasia species.

Story by Micah Visoiu, Department of Primary Industries and Water, Tasmania.

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