Scaevola tortuosa - Tortuous-stem Scaevola

Click image to enlarge

Scaevola tortuosa - Tortuous-stem Scaevola

This WA endemic plant is a poorly known inland species from the mallee region. It has a Priority One, Conservation Code rating, meaning it is known from generally less than 5 unprotected populations (not in a Reserve) and may be endangered from various threats. Currently it is recorded from the Goomalling region 120 km (75 miles) NE of Perth to the Norseman district 200 km (125 miles) North of Esperance. The photographs above were from a new colony 130 km (80 miles) NW of Esperance.

Scaevola tortuosa is a rhizomatous perennial, thereby producing many offshoot plants to create a colourful mat of dark green vegetation that is peppered with bright blue-purple/pink flowers. The soil is a coarse sand/clay and is sited in a drainage hollow that passes through a small clearing, which borders mallee woodland and a spaced (tall) Melaleuca habitat that is downstream from a small saltlake.

The Tortuous-stem Scaevola is named after its twisted flowering stem, of which those above without flowers and encountered in mid-September, were from a previous flowering season. The flowering stage above (blooming at ground level), were from an undeveloped inflorescence, which only started to grow around 4 weeks later when the new flowering stems (complete with buds) were produced. However these mostly did not develop and died off during a week of warmer than usual weather, although a few survived in the shade of taller vegetation.

Upon reflection, it is quite possible that the flowering stems are only produced when conditions are mild in their normally dry environment, with most resources being placed on producing the flowers at ground level. Alternatively, this species may begin to flower very much earlier than the recorded month of October. Certainly from my observations there would definitely be flowers in August, which had then finished by early October, although if local weather conditions had been more favourable, they would have continued a little longer.

Scaevola is part of the colourful and often ornamental Goodeniaceae family.

Scaevola humifusa - Procumbent Scaevola

Click image to enlarge

Scaevola humifusa - Procumbent Scaevola

The Scaevola genus has over 100 species and is the only one in the Goodeniaceae family to also occur outside of Australia, although most are Australian endemics and are distributed in all States. Many plants in this genus are shrubs, rather than short-lived herbs (more common in the other genera), so are frequently used in garden landscaping where they are also known as Fan Flowers. Scaevola humifusa is not officially recorded for the Esperance region, but does with the above, grow 90 km (55 mile) further east from its last most easterly range at Lake King.

Scaevola humifusa is normally found from Lake King to Ravensthorpe, then sweeps north to below Geraldton and returns to about 70 km north of the Lake King occurrence. The colony above had around 20 plants and was growing in a coarse sandy soil over a sand/clay base, where seepage flowed. This species is called the Procumbent Scaevola, as the stems trail over the ground but do not take root.

The fan-shaped flowers are little more than ½ cm (1/4”) across, but being numerous and combining with a compact cushion base, provide a visually attractive scene. As this plant was restricted to the seepage zone, it obviously requires the additional moisture from this habitat. Consequently, in this often dry region it would be highly dependent on the availability of seasonal rainfall and has been noted flowering anytime from August to January. The above were encountered 2-3 years after a fire, in late September of an average year.

Scaevola crassifolia – Thick-leaved Fan-flower

Click image to enlarge

Scaevola crassifolia – Thick-leaved Fan-flower

Scaevola is a genus from the large Goodeniaceae family and are commonly known as Fan-flowers. They are separated from genera like Lechenautia, Goodenia and others by only having 1-2 ovules (becoming seed when fertilised) per ovary, which generally produces larger seed that can have germination and seedling survival advantages in drier environments. Scaevola crassifolia is a near coastal shrub favouring calcareous (alkaline) soils commonly over limestone, these conditions dry rapidly without regular rainfall, so any small advantage can mean the difference between survival or not in such unsparing conditions.

The flexible leaves are not prickly, although are quite thick and slightly sticky to touch (viscid), but effective against salt spray and being sandblasted by strong coastal winds. In more sheltered gullies and amongst other vegetation they can grow to around 1.5 metres (5’), but are more often well under a metre (2'-3’) in exposed positions, although they can spread 3 metres (10’).

The Thick-leaved Fan-flower is a prolific bloomer and will produce over several months. The flowers are around 1.5 cm (over ½”) diameter and occur in compact spikes that open progressively, making them long flowering. In sandy calcareous coastal areas and offshore islands, this species can be found from above Karratha on the northwest coast to South Australia (almost to the Victorian boarder) on the southeast coast. That is something like 4500 km or 2800 miles, so a highly successful species!

For a plant to grow over such a large distance there are numerous colour forms from white to deep blue, but around Esperance, they tend to be mauve, or a light blue and occasionally white. Likewise flowering times will vary and are recorded from July to February, but locally October to December would be the main period, although some flowers are invariably found at other times.