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Electronic Flora of South Australia
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Electronic Flora of South Australia genus Fact Sheet

Family: Stylidiaceae
Stylidium

Citation: Sw. ex Willd., Sp. Pl. 4:146 (1805).

Derivation: Diminutive of Greek stylos, column; referring to the sensitive column consisting of the fused stamens and the style.

Synonymy: Not Applicable

Common name: Trigger-plants.

Description:
Annual or perennial herbs with leaves usually in a basal rosette rarely along the stems; leaves sessile or petiolate, alternate, opposite or whorled, usually entire or rarely with sharp serrations.

Inflorescence a thyrse with 1-few monochasia either corymb-like with younger flowers slightly overtopping the older ones, or raceme-like with monochasia reduced to single flowers (subtended by 2 bracts), usually glandular-pubescent; sepals scarcely connate or unequally fused to form 1 or 2 lips; corolla with a short tube and often split along the one side next to the labellum, zygomorphic with corolla lobes vertically or laterally paired rarely subequal and radiating; labellum (fifth petal) much shorter than corolla lobes, recurved and not irritable; column (fused style and stamens) usually irritable, recurved, with terminal anthers laterally and stigma below, resting in the labellum, but jerked erect when activated; ovary inferior more or less 2-celled with many ovules on a usually stalked central placenta.

Distribution:  136 species mainly in Australia but also from New Zealand to South-East Asia.

Biology: No text

Key to Species:
1. Perennials; leaves numerous in dense rosettes; flowers subtended by 2 sterile bracts
 
2. Leaves 5-30 cm long, in 1 basal rosette
S. graminifolium 4.
2. Leaves 0.5-0.9 cm long, in several rosettes along the stem
S. tepperanum 7.
1. Annuals; leaves alternate, opposite or if in rosettes then up to 8; flowers without sterile bracts
 
3. Ovary globular; sepals equally connate
 
4. Upper pair of petals truncate and variously lobed; column with a basal tooth
S. calcaratum 2.
4. Upper pair of petals with a rounded apex; column without a spur
S. perpusillum 6.
3. Ovary obconical; sepals unequally connate
 
5. Leaves along the stem and internodes visible at least between some of them; stem more or less fleshy
S. despectum 3.
5. Leaves in a basal rosette; stem fleshy below the leaf rosette
 
6. Corolla lobes radiating; column insensitive and not activated
S. beaugleholei 1.
6. Corolla lobes unequally laterally paired; column sensitive and activated by pollinators
S. inundatum 5.

Author: Not yet available


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