Hydrocotyle crassiuscula

Regional Species Conservation Assessments per IBRA subregion.

Least concern

Near threatened

Rare

Vulnerable

Endangered

Critically endangered

Extinct

Data deficient

Adelaide

Arkaroola

Ceduna

Coober Pedy

Hawker

Innamincka

Marla

Marree

Mount Gambier

Oodnadatta

Renmark

Wudinna

Keith

Yunta

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Hydrocotyle from the Greek 'hydro' meaning water and 'kotyle' meaning a dish or plate; alluding to the shape of the leaves which are slightly depressed in the centre. Crassiuscula meaning somewhat thick, possibly referring to the species very short but thick pedicels or rather thick leaves.

Endemic to South Australia and found only in the Fleurieu Peninsula and on Kangaroo Island, growing in moist shady or open places on grey sandy loam. Rare in South Australia but more common post fire.
Herbarium regions: Eyre Peninsula, Southern Lofty, Kangaroo Island
NRM regions: Adelaide and Mount Lofty Ranges, Eyre Peninsula, Kangaroo Island
AVH map: SA distribution map (external link)

A stout glabrous annual herb spreading stems to 30cm wide but not rooting at the nodes. Leaves to 15 mm across, divided into three oblong cuneate lobes, each with 2 or 3 short segments. Flowers tiny, pale yellow. Flowering between September and November. Fruit on short, rigid peduncles in umbels of 8-12 with fruiting pedicels to 1.5 mm long, thick. Mericarps with 1 row of tubercles between dorsal and intermediate ribs, and usually several tubercles between intermediate and inconspicuous lateral ribs. Seed embryo type is linear under-developed.

Collect seeds between October and December. Collect maturing fruits by picking off the clusters that are turning brown. Place the fruits in a tray and leave to dry for one to two weeks. Then rub the fruits with a rubber bung to dislodge the seeds. Use a sieve to separate the unwanted material. Store the seeds with a desiccant such as dried silica beads or dry rice, in an air tight container in a cool and dry place.

In 2020-2021 this species was assessed post-fire in 1 year old fire scars. A total of 136,00 seeds have been collected & banked for a population in Flinders Chase National Park. Germination screening testing the response to fire cues will be undertaken in 2021.This project was supported by the Project Phoenix program.

Location	No. of seeds (weight grams)	Number of plants	Date collected	Collection number Collection location	Date stored	% Viability	Storage temperature
BGA MSB	4,600 (1.27 g) 4,600 (1.27 g)	50+	8-Oct-2008	TST569 Kangaroo Island	2-May-2017	95%	+5°C, -18°C, -80°C
BGA	42,600 (12.82 g)	100	14-Nov-2019	DJD3884 Southern Lofty	24-Jun-2020	95%	-18°C, -80°C

Location: BGA — the seeds are stored at the Adelaide Botanic Gardens, MSB — the seeds are stored at the Millennium Seed Bank, Kew, England.
Number of plants: This is the number of plants from which the seeds were collected.
Collection location: The Herbarium of South Australia's region name.
% Viability: Percentage of filled healthy seeds determined by a cut test or x-ray.

Date	Result	T0	T50	Pre-treatment \| Germination medium \| Incubator: Photoperiod / Thermoperiod
Jul-16	0%	NA	NA	leached in water 24 h; 1% agar; Incubated under spring/autumn conditions
Jul-16	0%	NA	NA	leached in water 24 h; 1% agar; Incubated under winter conditions

Result: Maximum percentage of germination observed.
T0: Number of days before first germinant observed.
T50: Number of days to achieve 50% germination.
Pre-treatment: The initial treatment that the seeds received prior to placement on germination media.
Germination medium: The substrate that seeds were placed on for the duration of the germination experiment.
Incubator conditions:
Photoperiod: The duration of light exposure that the seeds were subject to during a 24 hour period.
Thermoperiod: The constant or diurnal temperatures that seeds were subject to during a 24 hour period.
Winter conditions: 15°C 20 h (3am→11pm); 5°C 4 h (11pm→3am) / 10 h light (8am→6pm); 14 h dark (6pm→8am)
Spring/Autumn conditions: 22°C 12 h (8am→8pm); 10°C 12 h (8pm→8am) / 12 h light (8am→8pm); 12 h dark (8pm→8am)
Summer conditions: 30°C 14 h (6am→8pm); 15°C 10 h (8pm→6am) / 14 h light (6am→8pm); 10 h dark (8pm→6am)

Kangaroo Island (KAN01)	Kanmantoo	Rare (IUCN: RA d(ii)) [fluctuates, fire ephemeral]
Fleurieu (KAN02)		Vulnerable (IUCN: VU D2) [fluctuates; fire ephemeral; flowers after fire; in Deep Ck, Mt Billy]