Plants of
South Australia
Heliotropium inexplicitum
Boraginaceae
Baffling Heliotrope
Display all 12 images

Etymology

Heliotropium from the Greek 'helios' meaning sun and 'tropos' meaning turn; probably alluding to an early belief that the flowers turned to face the sun. Inexplicitum from the Latin 'inexplicitus' meaning inexplicable; referring to the surprising lack of recognition accorded this species in herbaria.

Distribution and status

Found in the far north-western part of South Australia, growing on sandy & clay, often stony soils. Also found in Western Australia and Northern Territory. Native. Very rare in South Australia. Rare in Northern Territory. Common in Western Australia.
Herbarium regions: North Western, Lake Eyre
NRM regions: Alinytjara Wilurara, South Australian Arid Lands
AVH map: SA distribution map (external link)

Plant description

Annual to short-lived perennial herb, ascending to spreading-ascending, to 12 cm tall with long stiff white hairs on the stems, leaves and calyx. Leaves linear to oblong to narrowly elliptic to narrowly ovate, to 25 mm long and 2.5 mm wide, surface with the appressed hairs. Inflorescence short clusters at terminal with small white flowers, outer surface with hairs. Flowering between March and August. Fruits are brown oblong to suboblong to subovate capsule to 1.4 mm long and 0.9 mm wide, moderately to strongly pitted. Seeds are dark brown sectoroid seed to 1 mm long and 0.7 mm wide, with a smooth surface. Seed embryo type is spatulate fully developed.

Seed collection and propagation

Collect seeds between April and September. Collect mature capsule, those that are drying off, turning brown and contain dark, hard seeds inside. Can collect individual fruit cluster or break off whole heads. Place the capsules in a tray and leave to dry for one to two weeks. Then rub the fruits gently by hand 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. From one collection, the seed viability was high, at 90%.

Seeds stored:
  Hide
LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA320 (0.144 g)30+23-Apr-2015DJD3118
Lake Eyre
1-Jan-201690%-18°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.