Etymology
Isoetes from the Greek 'isos' meaning alike and 'etos' meaning year; referring to the submerged species remaining evergreen throughout the year. Attenuate from the Latin 'attenuatus' meaning drawn out, tapered; referring the leaves that narrow gradually to the tip.
Distribution and status
Known only from the type locality in the north-western side of Comaun Forest Reserve in South Australia, growing in an ephemeral swamp seasonally inundated with 20–40 cm of water and often grows with I. muelleri among sedges and grasses. Plants appear when soil becomes flooded and leaves die off after the swamp dries up in mid-summer. Native. Very rare in South Australia.
Herbarium region: South Eastern
NRM region: South East
AVH map: SA distribution map (external link)
Plant description
Amphibious herb with shallowly 3-lobed corm, to 10 mm wide. Leaves to 20, spirally arranged, erect, to 23 cm long and 1.5 mm diameter, flexible, attenuate, acute, bright green, with a base to 15 mm wide, broadly winged, white. Spore structures (sporangia) elliptic to round, to 7 mm long and 4 mm wide, opaque, dark brown. Microspores densely spiny, pale grey, spherical, to 0.6 mm diameter, with large tubercles, drying white. Fruits are megaspores found in the hollow leaf base. Seeds are pale grey megaspores, white when dried.
Seed collection and propagation
Collect seeds between September and December. Check to seed if the plant has any spores by pulling a leaf out of the ground from the base and looking inside the fat, hollow leaf base for a sack of white globular or flattened megaspores. If present, pull off a few of the leaves and place in a seal paper bags to prevent spores from fulling out. Leave the spores in the paper bag to dry. Then remove the leaf covering carefully to expose the spore sack. Store the spores in an air tight container in a cool and dry place or in a -20oC freezer.