Australian Crassula

Crassula sieberiana (Schultes & Schultes f.) Druce

Synonyms - Crassula exserta, Tillaea sieberiana, Tillaea verticillaris.

Family: Crassulaceae.

Names:

Crassula is from the Latin crassus meaning thick and referring to the fleshy leaves and stems.
Sieberiana honours the botanist Sieber.
Australian Crassula

Other names;

Australian stonecrop
Austral Stonecrop
Austral Crassula
Silver Crassula
Sieber Crassula

Summary:

A small, succulent, usually annual herb with red cored stems and compact clusters of white to red flowers.

Description:

Cotyledons:

Two. Round to oval, about 1.5 mm long and fleshy. Tip rounded to slightly pointed. Surface pimply and hairless.

First leaves:

Narrowly oval, fleshy, pimply with rounded tips. Hairless.

Leaves:

Opposite.
Petiole - None.
Blade - Bright green when young to red/brown usually as it matures, oval to lance shaped, fleshy, pimply, 1.5-6 mm long x 1-4 mm wide, almost flat on one side and convex on the other, slightly and abruptly constricted near the base. Stem clasping and densely packed around the stem. Tip sub acute to obtuse.

Stems:

Erect, sparsely branched, 15-150 mm tall, round, translucent with red centre to wiry and woody. Hairless. Forms a mat on the ground.

Flower head:

1- several , dense clusters in the axils of leaf like bracts. All together forming a leafy, interrupted spike.

Flowers:

White to red. In clusters in leaf axils. 4 or 5 Petals. bisexual, regular
Ovary - Superior with a small, flat, linear, white or pale yellow scale, 0.4-0.5 mm long at the base. 4 almost cylindrical carpels constricted into short styles or beaks.
Sepals - 4-5, 1-2 mm long, narrowly egg shaped. Tip acute and colourless.
Petals - 4-5, Red to pink or pale yellow or white. Lobes narrowly egg shaped, 1-1.5 mm long. Acute tip.
Stamens -
Anthers -

Fruit:

4 follicles, 1 mm long, on stalks 0.5-5 mm long, minutely warty or papillose, with small beak. Opens by an apical pore to release upper seed. Lower seed remains encased until the calyx decays. 2 seeds in each follicle.

Seeds:

Very small. Cylindrical with rounded ends. Surface usually smooth with rows of pimples.

Roots:

Shallow.

Key Characters:

One flower in the cluster on a longer pedicel.

Biology:

Life cycle:

Annual (rarely perennial). Germinates anytime with a peak in autumn to early winter. Most productive in winter and spring. Flowers late-winter/spring

Physiology:

Reproduction:

By seed.

Flowering times:

Summer in SA.
Spring to summer in NSW.
August to October in WA.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

C. exserta may be a subspecies of C. sieberiana (Australian Crassula).

Allelopathy:

Population Dynamics and Dispersal:

Spread by seed.

Origin and History:

Australia.

Distribution:

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate.

Soil:

Prefers sandy to loamy soils. Occurs on a wide range of soils.
Often found on saline mud flats, clayey depressions and granite rock outcrops.

Plant Associations:

Significance:

Beneficial:

Palatable but produces little bulk.

Detrimental:

Weed of crops, disturbed areas and wet areas.

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

Crassula (Crassula colorata) is very similar but has 5 petals, smaller cotyledons, broader young leaves, is pimply all over the plant and is more compact in habit.
Dense Crassula (Crassula decumbens)
Three-parted Crassula (Crassula alata)
Swamp Crassula (Crassula helmsii)
Crassula ciliata
Crassula glomerata
Crassula multicava
Crassula natans
Crassula tetragona

Plants of similar appearance:

Chickweed (Stellaria media)
Corn Spurrey (Spergula arvensis)
Four-leaved Allseed (Polycarpon tetraphyllum)
Mouse-eared Chickweeds (Cerastium spp.)
Pearlwort (Sagina apetala)
Pimpernel (Anagallis arvensis)
Waterblinks (Montia spp.)
Pigweed (Portulaca spp.)

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P391. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P189-190. Diagram

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P342. Photo.

Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). P57.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #366.8.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P205.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P99. Diagrams. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.