Citation: L., Sp. Pl. 683 (1753).

Derivation: Greek side, used by some classical authors to denote a pomegranate or a water-lily.

Synonymy: Not Applicable

Common name: Sidas.

Description:
Shrubs or undershrubs with stellate-tomentose indumentum; leaves petiolate, linear-oblong or lanceolate to reniform, ovate or orbicular, entire to crenate or toothed; stipules subulate, usually caducous.

Flowers bisexual, single on jointed and often bent peduncles or in racemes, not showy; epicalyx 0; calyx with 5 lobes longer or shorter than the tube; petals 5, yellow or orange; anthers numerous, on filaments arising from the top of a fairly long tube; carpels 5-10, in a single whorl, with 1 ovule in each cell; style-branches as many as the carpels, capitate, fused below; stigmas confined to the tips of the styles; lateral carpel walls with a thickened reticulate pattern.

Fruit a schizocarp usually separating readily into fruitlets (mericarps), elevated or flat at the apex, the fruitlets indehiscent or opening apically by 2 valves.

Distribution:  About 200 species in warmer parts of the world; about 35 native and 5 naturalised in Australia.

Biology: No text

Taxonomic notes: The density of leaf toothing is taken from the largest leaves on each specimen. The taxonomy of Sida in Australia is notoriously difficult, and the following treatment is an attempted improvement on the existing knowledge in the region. Fruit characters, little used in the past, are extremely valuable in separating species. Flowers are solitary or in twos in most of our species but often appear to be in racemes or clusters due to the late growth of the leaves. In a few species flowers occur along a distinct axillary rhachis with leaves bract-like or 0, solitary flowers also sometimes being present. J. Black (1952), Fl.S. Aust. 561, considered that S. platycalyx F. Muell. ex Benth., (1863) Fl. Aust. 1:197, a distinctive species with a large orbicular spinose "indehiscent" schizocarp occurring in neighbouring adhd regions of N.T., Qld and N.S.W., may extend into S.Aust. However, it has not been found in the State. A number of species have previously been misidentified as others occurring in the State; no attempt has been made, except as included in synonymy, to indicate the misapplication of these names. Sida cordifolia L. (1753) Sp. Pl. 684, a pantropical species occurring in northern Australia, was collected in 1978 as a "weed in garden near tropical fruit" at Ernabella (NW). Like S. rohlenae it has awned mericarps, but it differs by its large ovate-cordate leaves, its dense persistent tomentum throughout, its dense axillary clusters of several flowers and its peduncles 3-8 mm long and in our material not enlarging in fruit.

Key to Species:

1. Schizocarp with 6-9 prominent radiating wings between adjacent carpels; a sparsely pubescent perennial; calyx 2.5-3 mm long in flower; corolla c. 5 mm long	S. goniocarpa 7.
1. Schizocarp not winged, with a groove between adjacent carpels
2. Calyx 1.5-2.5 mm long; schizocarp 3-4 mm diam.; leaves 3-6 rarely 10 mm long	S. intricata 8.
2. Calyx 2.5-12 mm long; schizocarp 3.5-10 mm diam.; leaves 5-55 mm long
3. Calyx prominently 10-ribbed especially towards the base; mericarps conspicuously 2-awned	S. rohlenae 10.
3. Calyx not ribbed; mericarps cleft at the apex but not awned
4. Calyx lobes narrow-triangular, narrow-acuminate, obscured by a dense thick often brown tomentum; schizocarp densely pubescent	S. phaeotricha 9.
4. Calyx lobes broad-triangular, obtuse or acute or shortly broad-acuminate, not or hardly obscured by pubescence; schizocarp glabrous or pubescent
5. Flowers single or in groups subtended by tiny bracts or only by stipules, spaced along an elongated rhachis
6. Calyx 5-8 mm long in flower and fruit; rhachis 8-300 mm long; corolla 7-10 mm long; schizocarp 8-10 mm diam., with 9-12 mericarps	S. cunninghamii 4.
6. Calyx 2.5-4.5 mm long in flower, hardly longer in fruit; rhachis up to 50 mm long; corolla 4-6 mm long; schizocarp 3.5-4.5 mm diam., with 5-8 mericarps
7. Leaves thinly pubescent, with blade narrow-ovate to narrow-oblong, much longer than the petiole, 2-11 mm wide; flowers on a rhachis subtended .by stipules 0.5-1.5 mm long; calyx 3-4.5 mm long; schizocarp 4-4.5 mm diam., deeply grooved between carpels, glabrous, rugose on sides, raised in the centre, with 5 mericarps	S. ammophila 1.
7. Leaves roughly tomentose, narrow-oblong to transverse-ovate, equal to twice the length of the petiole, 5-30 mm wide; flower clusters subtended by stipules 1.5-3.5 mm long; calyx 2.5-3 mm long; schizocarp 3.5-4 mm in diam., obscurely grooved between carpels, persistently puberulent, shallowly rugose on sides, hardly raised in the centre, with 5-8 mericarps	S. fibulifera 5.
5. Flowers one to few in axils, not borne on an elongated rhachis, sometimes appearing as if in racemes or clusters through an occurrence in shoots with small developing leaves
8. Schizocarp hardly rugose on sides; an elongated rhachis with clusters of stipules invariably present somewhere on the specimen	S. fibulifera 5.
8. Schizocarp rugose on sides
9. Schizocarp glabrous, the central apical region prominently raised, with rugose sides
10. Mericarps 5; leaves thinly pubescent, narrow-ovate to narrow-oblong; pedicel 8-20 mm long; corolla 4-5 mm long	S. ammophila 1.
10. Mericarps 5-8; leaves thickly tomentose
11. Leaves with the blade 1 or 2 times the length of the petiole, coarsely serrate with 2-4 teeth/cm; corolla 5-6 mm long	S. corrugata var. A 3c.
11. Leaves with blade 2-10 times longer than the petiole, serrate to entire, with 3-12 teeth/cm; corolla 7-12 mm long
12. Calyx in flower 5-12 mm long, with lobes 2-3 or more times the length of the tube; leaf blades 15-60 mm long, cuneate to subeordate at the base, smooth-tomentose	S. calyxhymenia 2.
12. Calyx in flower 3.5-4 mm long, lengthening to 6 mm in fruit, with lobes more or less equalling the tube; leaf blades 5-22 mm long, rounded to cordate at the base, coarsely tomentose	S. filiformis 6.
9. Schizocarp persistently pubescent, the central apical region flat to rounded, hardly raised above, with obscurely to deeply rugose sides
13. Schizocarp 8-10 mm diam., with 9-12 mericarps; peduncle 30-50 mm long; leaves thickly but smoothly tomentose	S. cunninghamii 4.
13. Schlzocarp 3.5-7 mm diam., with 5-8 mericarps
14. Schizocarp obscurely grooved between carpels, almost smooth, the sides only obscurely rugose; leaves roughly tomentose; peduncle to 25 mm long; corolla 4-6 mm long	S. fibulifera 5.
14. Schizocarp conspicuously grooved between carpels, the sides rugose
15. Corolla 5-6mm long; pedicel 3-15 mm long; leaves with blade 1 or 2 times the length of the petiole, coarsely crenate-serrate with 2-4 teeth/cm, thinly pubescent, glabrescent, grey-blue below; plants prostrate to decumbent
16. Leaves with blade orbicular to ovate, 5-22 mm wide, with a cordate to rounded base	S. corrugata var. corrugata 3a.
16. Leaves with blade ovate to narrow-oblong, 4-14 mm wide, with a rounded to truncate base	S. corrugata var. angustifolia 3b.
15. Corolla 7-14 mm long; pedicel 12-60 mm long; leaves with blade 1.5 to more than 2 times as long as the petiole, serrate to almost entire, with 3-12 teeth/cm
17. Leaves and branches tomentose; calyx 5-12 mm long in flower, with the lobes 2-3 or more times the length of the tube; shrub to 2 m high	S. calyxhymenia 2.
17. Leaves and branches sparsely pubescent; calyx 3-4 mm long, hardly enlarging in fruit, with lobes more or less equalling the tube; sprawling to erect perennial 0.2-0.5 m high	S. trichopoda 11.

Author: Prepared by W. R. Barker and J.P. Jessop