1	"Ovules 4–10, in 2 rows. Hypanthium (both in flower and fruit) with 9–16 irregular longitudinal ribs, ± obconic"	2
1	"Ovules 2, collateral. Hypanthium smooth to rugose or with regularly arranged, antisepalous and/or antipetalous, longitudinal ribs, of varied shape (but when ribbed usually not obconic)"	12
2	"Stamens 15–40, in 2 series"	3
2	"Stamens 5–13, in 1 series"	5
3	"Mature peduncles 0.7–1.4 mm long. Sepals c. 1.4 mm long. Mature style c. 0.7 mm long. Ovules 4"	"Thryptomene duplicata"
3	"Mature peduncles 0–0.3 mm long. Sepals 2–3.3 mm long. Mature style 2.5–3.5 mm long. Ovules 5–10"	4
4	"Leaves with numerous, crowded oil glands. Ovules 8–10"	"Thryptomene sp. Leinster (B.J. Lepschi & L.A. Craven 4362)"
4	"Leaves with many, separated oil glands. Ovules 5–8"	"Thryptomene decussata"
5	"Stamens 5, opposite the sepals"	"Thryptomene salina"
5	"Stamens 7–13, not all opposite the sepals"	6
6	"Stamens 7–13, irregularly arranged, with some opposite and some between the sepals and petals"	7
6	"Stamens 10, one opposite each sepal and ± opposite each petal"	9
7	"Leaves fairly flat, obovate to almost circular; apical mucro or point 0.2–0.5 mm long. Bracteoles persistent in fruit. Ovules 4"	"Thryptomene johnsonii"
7	"Leaves thick, linear to obovate in outline; apical point 0.5–1.5 mm long. Bracteoles deciduous. Ovules 5–8"	8
8	"Leaves triangular or indented-triangular in TS towards the apex and tending to be more flattened below, 3–9 mm long, tapered at apex to a terminal point 0.5–1 mm long"	"Thryptomene australis"
8	"Leaves almost terete with an adaxial groove, 2.5–4 mm long, with a subterminal point 0.8–1.5 mm long"	"Thryptomene eremaea"
9	"Leaf apex with a point 1–2 mm long. Mature style 0.3–0.6 mm long. Ovules 6–9"	"Thryptomene costata"
9	"Leaf apex entire or with a point up to 0.5 mm long. Mature style 0.6–0.8 mm long. Ovules 4–6"	10
10	"Rapidly growing young stems not winged. Hypanthium ribs flattened and closely pressed together giving a striate appearance"	"Thryptomene striata"
10	"Rapidly growing young stems narrowly 4-winged. Hypanthium ribs rounded to almost acute and separated by v-shaped sinuses"	11
11	"Leaf blades narrowly to broadly obovate, 2–7 × 0.9–2.1 mm; mucro 0–0.3(–0.4) mm long"	"Thryptomene mucronulata"
11	"Leaf blades broadly obovate, 2–3 × 1.8–2.3 mm; mucro 0.4–0.5 mm long"	"Thryptomene sp. Coolgardie (E. Kelso s.n. 1902)"
12	"Anthers with longitudinally dehiscent thecae, the slits about as long as the thecae. Hypanthium urceolate in fruit"	13
12	"Anther dehiscent by pores or short slits that are much shorter than thecae. Hypanthium of varied shape, rarely urceolate"	16
13	"Leaves broadly or very broadly obovate, broader than thick, not or scarcely pointed. Hypanthium tending to develop a whitish bloom"	"Thryptomene planiflora"
13	"Leaves linear in outline to broadly obloid-ellipsoid, about as thick as wide or thicker than wide, usually mucronulate to prominently pointed but sometimes ± absent in
T. urceolaris. Hypanthium lacking a bloom"	14
14	"Leaves linear to narrowly oblong in outline, 4–9.5 mm long; apical point 0.7–1.4 mm long. Hypanthium distinctly 10-ribbed in young fruit, becoming smooth at maturity"	"Thryptomene cuspidata"
14	"Leaves clavate or obovate to narrowly oblong in outline, 1.4–3.5(–4) mm long; apical point absent or up to 0.8(–1) mm long. Hypanthium not or scarcely ribbed in young fruit"	15
15	"Mature leaves distinctly angled between the two surfaces, 2–4 mm long; apical point recurved, 0.3–1 mm long. Peduncles 0.5–1.5 mm long. Flowers 2.5–4 mm diam."	"Thryptomene kochii"
15	"Mature leaves clavate (rounded not angled), 1.4–2.5 mm long; apical point absent or erect, up to 0.2 mm long. Peduncles 0.3–0.5 mm long. Flowers 4–5.5 mm diam."	"Thryptomene urceolaris"
16	"Anthers with thecae close together, of varied colour. Fruiting hypanthium longer than broad, sometimes bilaterally compressed. Seed longer than broad in most species, of very varied shape. Extending from the west coast to the east coast and south to Tasmania, but absent from the far north"	17
16	"Anther thecae well separated at base, usually dark brown. Fruiting hypanthium usually much broader than long, never bilaterally compressed. Seed transversely reniform or of various other depressed shapes. Occurring in northern and western Australia"	25
17	"Petals 6 in all or most flowers"	"Thryptomene naviculata"
17	"Petals 5 in all or most flowers"	18
18	"Sepals slightly or distinctly longer than the petals"	19
18	"Sepals as long as or shorter than the petals"	20
19	"Leaves flat or with incurved margins or thick. Fruits with peduncle usually 1–2 mm long, if peduncle shorter then fruits 10-ribbed"	"Thryptomene sp. Mt Clara (R.J. Cranfield 11702)"
19	"Leaves somewhat folded inwards. Fruits smooth, with peduncle 0.5–0.7 mm long"	"Thryptomene sp. Wandana (M.E. Trudgen 22016)"
20	"Outermost sepal strongly ridged, sometimes shortly horned. Hypanthium quite compressed in fruit, saccate near the peduncle"	"Thryptomene elliottii"
20	"Outermost sepal not horned. Hypanthium terete or somewhat compressed in fruit, not saccate"	21
21	"Leaves very thick, almost terete, with a prominent apical point 0.2–1.5 mm long"	"Thryptomene biseriata"
21	"Leaves flattened, apical point absent or not more than 0.2 mm long"	22
22	"Leaves broadly or very broadly obovate, somewhat folded. Hypanthium becoming smooth in fruit. Peduncles 1 per axil"	"Thryptomene sp. Wandana (M.E. Trudgen 22016)"
22	"Leaves linear in outline to narrowly obovate or narrowly oblong, not folded. Hypanthium 10-ribbed in fruit. Peduncles 1 or 2 per axil"	23
23	"Leaves 2–3.5 mm wide"	"Thryptomene sp. Warburton (M. Henson & M. Hannart 32433)"
23	"Leaves 0.6–1.3 mm wide"	24
24	"Leaves not clustered, 3–5 mm long, 0.4–0.5 mm thick"	"Thryptomene nealensis"
24	"Leaves tending to be densely clustered near the ends of branchlets, 6–16 mm long, fairly flat or up to 0.3 mm thick"	"Thryptomene wittweri"
25	"Sepals widely spreading or with distal half widely spreading in fruit, more than half as long as to slightly exceeding the petals"	26
25	"Sepals fairly erect to tightly closed inwards in fruit, much shorter than petals in many species but more than half the length of the petals in a few species"	29
26	"Leaves long-linear in outline, thick; apical point recurved, c. 1 mm long. Stamens 7 or 8, almost equidistant, irregularly arranged in relation to the sepals and petals"	"Thryptomene pinifolia"
26	"Leaves depressed ovate or circular to almost linear, not very thick but with margins incurved; apical point absent or up to 0.3 mm long. Stamens usually 10 alternating with the sepals and petals, occasionally 9 with a pair of stamens reduced to a solitary antisepalous stamen"	27
27	"Sepals with a herbaceous oil-dotted keel and scarious margins. Stamens c. 1/3 as long as the petals"	"Thryptomene hubbardii"
27	"Sepals without an obvious keel, rather petaloid. Stamens 1/2–2/3 as long as the petals"	28
28	"Leaves broadly ovate to depressed-obovate, often ± circular, the broadest ones 2.3–3.3 mm wide. Flowers 5–8 mm diam. Stamen filaments 1.2–1.6 mm long"	"Thryptomene orbiculata"
28	"Leaves very narrowly to broadly obovate, rarely almost circular, the broadest ones 1–2.5 mm wide. Flowers 3.5–6 mm diam. Stamen filaments 0.7–1.3 mm long"	"Thryptomene racemulosa"
29	"Flower buds with apex concave to flat. Bracteoles mostly persistent in mature fruit and sepals closed in almost horizontally in fruit"	30
29	"Flower buds with apex usually convex to conic or flat in most species, but flat to concave in T. podantha. Bracteoles caducous to persistent, if persistent then sepals fairly erect or only loosely closed inwards in fruit"	35
30	"Leaves 5–12 times longer than wide, not keeled. Hypanthium pitted in fruit"	31
30	"Leaves ranging from slightly wider than long to 4 times longer than wide, often strongly keeled. Hypanthium smooth in fruit or with irregular wrinkles and bumps, sometimes pitted in between"	32
31	"Leaves with 2 or 3 main rows of oil glands on each side of the midvein; glands 20–40 per row. Sepals glossy"	"Thryptomene calcicola"
31	"Leaves with 1 or 2 rows of oil glands on each side of the midvein; glands 8–15 per row. Sepals dull"	"Thryptomene stenophylla"
32	"Hypanthium smooth in fruit"	"Thryptomene nitida"
32	"Hypanthium rugose in fruit"	33
33	"Leaves 2.5–7 × 0.7–2 mm, much longer than broad. Seed (where known) 1.5–1.7 mm across"	"Thryptomene sp. Carrarang (M.E. Trudgen 7420)"
33	"Leaves 1.2–3(–3.5) × 0.6–2.2 mm long, c. 1/2 as broad as long to broader than long. Seed (where known) 1.2–1.5 mm across"	34
34	"Leaves with 1 or 2 rows of prominent oil glands on each side of midvein, not folded. Hypanthium rugose with numerous low rounded bumps. Occurring in hilly terrain"	"Thryptomene baeckeacea"
34	"Leaves usually with 3–5 rows of oil glands on each side of midvein, usually folded. Hypanthium with longitudinal wrinkles. Occurring on coastal dunes and limestone"	"Thryptomene dampieri"
35	"Hypanthium ribbed in flower, becoming smooth or almost smooth in mature fruit, if not fully smooth then with a distinct pedicel as well as a peduncle"	36
35	"Hypanthium variously ornamented in flower, not becoming smooth in fruit, the pedicel ± absent"	37
36	"Bracteoles deciduous. Petals 2–2.5 mm long. Stamen filaments 0.6–1 mm long. Fruits with a peduncle 0.5–1.5 mm long and a pedicel 1–1.4 mm long"	"Thryptomene podantha"
36	"Bracteoles persistent after fruits fall. Petals 3–3.5 mm long. Stamen filaments c. 1.7 mm long. Fruits with a peduncle less than 0.2 mm long and no pedicel"	"Thryptomene spicata"
37	"Bracteoles caducous or deciduous. Sepals folded and with an acute apex"	38
37	"Bracteoles mostly persistent in fruit, if caducous then sepals with a rounded apex"	41
38	"Sprawling coastal dune plant, rooting at nodes of prostrate stems. Mature style c. 1.3 mm long, almost as long as the petals"	"Thryptomene repens"
38	"Erect to widely spreading shrub, without adventitious roots, occurring inland or near coast but not on dunes. Mature style 0.3–0.8 mm long, much shorter than the petals"	39
39	"Stamens filaments 0.25–0.4 mm long. Mature style 0.3–0.4 mm long. Hypanthium longitudinally furrowed in fruit"	"Thryptomene strongylophylla"
39	"Stamens filaments 0.4–0.8 mm long. Mature style 0.5–0.8 mm long. Hypanthium rugose-tuberculate in fruit"	40
40	"Sepals usually 0.5–0.8 mm long. Stamen filaments usually 0.4–0.6 mm long"	"Thryptomene caduca"
40	"Sepals usually 0.8–1.5 mm long. Stamen filaments usually 0.6–0.8 mm long"	"Thryptomene sp. Eagle Gorge (A.G. Gunness 2360)"
41	"Hypanthium (in flower) rugose with wrinkles or ridges as well as pits. Outer sepals distinctly auriculate"	42
41	"Hypanthium (reticulate-pitted. Outer sepals not or scarcely auriculate"	44
42	"Mature peduncles 0.5–2.5 mm long. Sepals with a prominent keel, distinctly denticulate to laciniate, with margins often recurved or flat, not markedly incurved"	"Thryptomene denticulata"
42	"Mature peduncles ± absent, 0–0.3 mm long. Sepals not keeled, ± entire, with margins incurved"	43
43	"Leaves with the apex (of the dorsal ridge) incurved. Bracteoles with the keel forming a prominent compressed ridge"	"Thryptomene globifera"
43	"Leaves mostly with the apex (including dorsal ridge) recurved. Bracteoles with the midrib not very prominent"	"Thryptomene wannooensis"
44	"Peduncles solitary or 2 superposed in the axils, 1–3-flowered. Occurring near the south coast, mainly on granite"	"Thryptomene saxicola"
44	"Peduncles solitary in the axils, all 1-flowered or rarely a few of them 2-flowered. Occurring north of Perth, mainly on sand or laterite"	45
45	"Leaves 1.2–2.2 mm long. Mature peduncles 0.8–3 mm long, shorter than to about twice as long as the bracteoles. Bracteoles persistent"	"Thryptomene shirleyae"
45	"Leaves 3.5–12 mm long. Mature peduncles 3–11 mm long, much longer than the bracteoles. Bracteoles usually caducous or deciduous"	46
46	"Hypanthium (in mature fruit) with large deep pits, not papillose. Occurring south of Geraldton"	"Thryptomene hyporhytis"
46	"Hypanthium (in mature fruit) with numerous small shallow pits, sometimes also papillose. Occurring north and east of Geraldton"	47
47	"Mature peduncles 7–11 mm long. Bracteoles 0.5–1 mm long. Hypanthium not papillose in fruit"	"Thryptomene stapfii"
47	"Mature peduncles 4–8 mm long. Bracteoles 1.5–2.4 mm long. Hypanthium minutely papillose in fruit"	"Thryptomene velutina"