Solanum pusillum A.R.Bean, Austrobaileya 6: 730 (2004).
T: Qld: western road,
Prostrate or sprawling, herbaceous resprouter, 0.1-0.3 m high. Juvenile stage absent. Adult branchlets brown or green; prickles 10-50 per decimetre, straight, acicular, 1-9 mm long, 10-16 times longer than wide; stellae sparse to dense, 0.8-1.2 mm diameter, stalks 0-0.1 mm long; lateral rays 4-7, porrect; central ray 0.8-1.5 times as long as laterals, not gland-tipped; finger hairs absent; Type 2 hairs absent, or sparse.
Adult leaves elliptical or ovate, deeply lobed throughout; lobes 2-4 on each side, acute or obtuse, lobing index 2.3-4; lamina 3-5.5 cm long, 1.4-2.5 cm wide, 1.6-2.2 times longer than broad, apex obtuse or acute, base cuneate, oblique part 0-3 mm long, obliqueness index 0-7 percent; petioles 0.8-1.8 mm long, 8-18% length of lamina, winged, prickles absent or present. Upper leaf surface green; prickles 10-50, straight, acicular, 2-8 mm long, prickles present on midvein and lateral veins; stellate hairs distributed throughout; proto-stellae present; ordinary stellae very sparse to sparse, 0.8-1.7 mm apart, 0.3-1.1 mm across, sessile; lateral rays 1-4, porrect or ascending; central ray 1-4 times as long as laterals, not gland-tipped; finger hairs present, 0.5-3 mm apart, not gland-tipped, 0.8-1.3 mm long; Type 2 hairs present throughout, 0.1-0.4 mm apart. Lower leaf surface green, or yellowish; prickles 4-17, straight, acicular, present on midvein and lateral veins; stellae sparse to moderate, 0.2-1 mm apart, 0.7-1 mm diameter, stalks 0-0.1 mm long; lateral rays 4-7, porrect; central ray 0.8-1.5 times as long as laterals, not gland-tipped; finger hairs absent; Type 2 hairs present throughout, 0.05-0.2 mm apart.
Inflorescence supra-axillary, solitary or pseudo-umbellate, common peduncle absent; 1-3-flowered, strongly andromonoecious, flowers 5-merous; pedicels 3-6 mm long at anthesis, same thickness throughout or markedly thicker distally, 0.4-0.6 mm thick at mid-point, prickles present. Calyx tube 1.5-2 mm long, lobes deltate, 1.5-3 mm long; prickles present at anthesis, 20-35 per flower, 2.5-6 mm long; stellae sparse to moderate, white, 0.7-1.1 mm across, sessile, lateral rays 4-8, central ray 1-1.5 times as long as laterals, not gland-tipped; finger hairs absent; Type 2 hairs present. Corolla white, 7-10 mm long, deeply lobed, inner surface glabrous; anthers 3-4 mm long; ovary with Type 2 hairs only; functional style 4-4.5 mm long, erect, with Type 2 hairs only.
Fruiting calyx with lobes less than or more than half length of mature fruit. Mature fruits 1 per inflorescence, globular, c. 15 mm diameter, green, 2-locular; placenta in cross-section sessile, semi-circular; mesocarp moist but not juicy; exocarp 0.8-1.3 mm thick; pedicels 12-18 mm long in fruit, 0.9-1.5 mm thick at mid-point; seeds pale yellow, 3.8-4 mm long.
Description by Bean reproduced, with permission, from Austrobaileya 6: 730 (2004).
A detailed description by Bean can be found at http://delta-intkey.com/solanum/www/pusillum.htm
Distribution and ecology
A poorly known species known only from the Dingo and Blackwater areas of the Leichhardt District in central coastal Qld.
Flowering and fruiting specimens have been collected in October and November.
Part of the S. hystrix group of subgen. Leptostemonum according to Bean (2004).
S. pusillum is most closely related to S. adenophorum. The two species overlap in distribution but differ by
- presence of stellate hairs on the branches, leaves and calyces in S. pusillum, these absent in S. adenophorum
- 1-3-flowered inflorescence in S. pusillum, 4-8-flowered in S. adenophorum
Derivation of epithet
From the Latin pusillus, tiny, a reference to the small size of the plant.
QLD: LEICHHARDT DISTRICT: Junee Tableland, N of Dingo, Nov 1990, Bean 2604 (BRI); near eastern road, Junee Tableland, N of Dingo, Oct 2002, Bean 19399 (BRI); eastern edge of S.F.236, SW of Blackwater, Nov 2002, Bean 19519 (BRI, MEL); ditto, Bean 19525 (BRI); S of Triumph Ck, c. 30 km SW of Blackwater, Nov 2002, Bean 19538 (BRI).
As cited in Bean (2004).
Plant status, if any
In first describing S. pusillum, Bean (2004) recommended a category of “Near Threatened” under IUCN guidelines (IUCN, 2001) since it was not included in any conservation reserve and only 7 subpopulations were known, four of these being on the Junee Tableland.
From the web
Images of S. pusillum plants can be accessed through Bean's Solanum site at http://delta-intkey.com/solanum/www/pusillum.htm
Further information and links for this species can be found on the Solanaceae Source site.