Weeds – some are worse than others – but why?
Our weed of the month for May is not a big threat at Cape Jervis – yet, and maybe never, but we will watch and act if necessary. The worst important weeds for any given area can be different but there are formal processes for classifying weeds. There are 32 weeds that have widespread impact, and are listed as “Weeds of National Significance”, based on their invasiveness, potential for spread and environmental, social and economic impacts (http://www.environment.gov.au/ biodiversity/invasive/weeds/weeds/lists/wons.html). We have two of these on site, bridal creeper and boxthorn. Each state also has its own “Declared Weeds”, that land holders are required to control on their own land (http://www.pir.sa.gov.au/biosecurity /weeds_and_pest_animals/weeds_in_sa). Other weed threats, such as Acacia cyclops are more localised. Woody weeds such as olive and cyclops are a BIG problem in the biodiverse coastal heathlands at the Cape because of their rapid growth and their smothering effect. Come out with us for a few hours and we can show you the benefits of removing these weeds and help you recognise young seedlings so they can be removed before they become a big problem.
Photos: hand-pulled ‘cyclops’ seedlings (E. Cousins); resprouting poisoned olive; a sea of baby olives (C. Schultz).
(Photos: E. Cousins, plant; C. Schultz, close-up of stem, at Cape Jervis)
This plant is from the same family as the quandong (Santalaceae) though you wouldn’t think so from the differences in the fruit or foliage!
‘Aphyllus’ is from the Greek, meaning ‘without leaves’. There are in fact leaves on the thick, rigid branches, but they are TINY (less than 1mm), more like scales! And expecting a cherry-like fruit or two? Try a small black ovoid (egg-shape) with a squashed creamy-red base (hence ‘Exocarpus’: ‘outside the nut’). Even the yellow flower clusters are small, at less than 4mm. These are present over spring and early summer, and protrude from the branches on short stalks. Tiny leaves, tiny flowers, tiny fruit… yet the olive-green bush can grow over 3.5m tall, with heaps of branches! Although common in many other parts of Australia, it is classed as ‘vulnerable’ on the Fleurieu Peninsula.
(Photos: E. Cousins; foliage, young flower and bud; bees on mature flower.)
Such a beautiful flower, and such beautiful foliage! A native of WA, this makes a lovely garden plant…just not so lovely when it escapes into local native bushland! The small bushy tree has flat blue-green leaves, reminiscent of acacias or eucalypts. The edges of the leaves can be tinged with red, while strong vein markings give a striped look so the leaves are fairly distinctive. The autumn and winter flowers though give the plant its common name. On breaking out of their capsules the white protruding stamens are firstly bent, then straighten out like pins from a red base. As you can see from the second photo above, the bees LOVE the nectar these flowers produce (there were more than one dozen of them clustered in that one flower)! Grow one in your own garden, but please, make sure it doesn’t spread elsewhere!
(Photo: E. Cousins, Cape Jervis; habit, stem)
This summer grass was pointed out to us by Corey Jackson (Yankalilla Council/NRM) on our site at Cape Jervis. Why knotty-butt? Well, the rootstock of the grass apparently looks knotted! Why ‘constricta’? Read on! Classified as ‘near threatened’, this grass seems to be doing well this year with the extra rain and cooler temperatures. It grows as a tussock pretty low to the ground at about 20-30cm in height, with a width roughly the same. The grass blades are just 2-3mm wide. The stem bearing the seeds (the ‘inflorescence’) is only about as high as the plant, but much branched. The seeds themselves have no bristles, are about 2-3mm long and with a constriction about ¼ of the way up from the base… so take your magnifier along if you go looking for this one! Possibly a good plant for finches, wrens, and other grass-seed eating birds. Let us know if you see any birds eating the seeds!
(Panicum capillare var. brevifolium)
(Photos: E. Cousins; growth habit, emerging flower head or inflorescence)
The mild, damp summer was kind to weeds as well our ‘good’ plants on site this year. This weedy grass was producing lots of seed when we came across it at our February working bee. It is a hairy, tufted grass…check those hairs out in the second photo! Notice also the slight purple in the plant, and the dominant midrib on the leaf. You might be able to spot all the ribbing on the stems as well. The flower head is very open and wide, at up to 40cm, with many branches. Single spikelets, each containing two flowers (one of which is fertile, the other sterile), adorn these branches. Unlike the leaves and stem, these spikelets aren’t hairy, but rough! Later, the mature flower head, full of seed, breaks off as a single structure, blowing away to spread the seed.
SCENTED MAT RUSH
(Photos: E. Cousins, flowering plant; C. Schultz, leaves, leaf tips, Cape Jervis)
Lomandras, or mat rushes, are tufted, normally shin-high perennials with long, narrow, bluey-green leaves that are quite tough. There are several varieties growing at Cape Jervis, but this particular one, the scented mat rush, is probably the easiest to identify. How? Check out the tops of those blade-like leaves… they generally have rabbit ears! That is, instead of a single point at the end of the leaf, there are two sharp tips. It looks like the leaf has been eaten or otherwise damaged! From winter to spring, there are pretty clusters of creamy-white, scented flowers hidden in amongst the foliage. If you look carefully you might see that some plants have different flowers; although the separate male and female plants are hard to tell apart until they have seed. So start looking for these pretty soon in some grasslands near you!!
(Photos: E. Cousins; flower, patch of plants)
When you first see these flowers emerging in spring, you might think they are freesias. The flower has a similar ‘bent tubular’ look to it, and the leaves are flat, shin high and much the same green. However, they are really quite different. Freesia flowers form a group like a pan pipe, with about 5 per stem. Here, though, there is a single flower per stem. The flower itself is almost white in colour, with touches of yellow and purple…another difference. Also, the leaves are less pointy at the top, with a prominent centre vein.
LIMESTONE SPIDER ORCHID
(Photos: E. Cousins, a patch at Cape Jervis, closer view of the flower)
We were lucky enough to see an extensive colony of these little beauties flowering at Cape Jervis in late August. A spider orchid … but which one? We first thought the veined spider orchid (Caladenia reticulate) but the fringe is white not burgundy. Other contenders were ruled out by size or locations. Not being orchid experts, we searched several books, looked at countless images online and finally got the definitive answer from Rosalie Lawrence, courtesy of SA Natureteers. Rosalie tells us this orchid is widespread in SA, but not the Adelaide Hills. Guess they don’t have the limestone base Cape Jervis has! Among the features distinguishing this from the Arachnorchis (Spiders) family is that there are not two yellow glands at the base of the column, just a yellow glow. Many thanks, Rosalie!!
(Photos: C. Schultz, a single flower, and a small clump with lots of buds at Cape Jervis)
This scented South African garden plant is now naturalised in many areas of bushland in South Australia. You won’t see it just yet though. Dormant over summer, the underground corms (bulbs) are waiting for winter-spring, when the soft, pale green leaves appear. These individually are flat, but together form a fan shape. The flowering stem can grow to about 40 cm, with kinks just before each of the flowers. The kinks give the flower head a look like a pan flute! The 6 ‘petals’ of the flowers are 3-5mm long, fused together at the base. In the bushland runaways, these petals are normally a creamy white, with possible hints of purple. Modern hybrid cultivars often come in many other colours but are not as scented though.
COMMON STORKS BILL
(Photos: E. Cousins, plant, close-up of flower; Cape Jervis. http://www.cabi.org/isc/datasheet/21843 ripe fruit )
Shin high, with deeply divided leaves, this weed loves disturbed or arid sites. There it will outcompete native plants. The annual weed has a rosette of deep green leaves at the base, which might produce a bit of stem as it grows older. From the basal leaf rosette, slender stalks grow, supporting a small cluster of flowers. The flowers are 5-petalled and pink, each petal roughly elliptic in shape, 4-6mm long.
It is the long seed pods though that give the plant its common name. These grow as a ‘beak’ 3-4 cm long. As they ripen and dry, they twist to produce the corkscrew seen in the photo on the right. At this stage the feathery seeds are released into the air. Another Erodium, with the common name of Long Storks Bill, produces a beak up to 10cm long!