Weed of the Month – June 2016

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PASPALUM

(Paspalum dilatatum)

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(Photos: E. Cousins, growth habit; http://www.dpi.nsw.gov.au/__data/assets/image/0007/199204/paspalum-190.jpg, seed head.)

This fairly common broad-leafed perennial from the Poaceae family is an exotic from South America. The plant will grow quite tall;  some at Cape Jervis are up to 1m high.  It grows in tussocks, with bright green, almost hairless leaves that tend to fold over near the bottom. The tussocks spread from short rhizomes underground, allowing the grass to recover quickly if grazed. Sadly for us, it is spreading into one of our good native patches at Cape Jervis. It is easily recognized from the seed heads. The purple-green seeds look like they are arranged in double rows very symmetrically along several branches, radiating out from the top of the flower stem. These are often sticky, which you will know if you play backyard cricket near them (in fact one common name for paspalum is sticky grass).

Plant of the Month – June 2016

WINDMILL GRASS

(Chloris truncata)

 

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(Photo: E. Cousins, Cape Jervis; single stalk of seed head, patch of grass, close-up of one seed head spike)

This native summer grass was flourishing at Cape Jervis after those lovely February rains, and the warm weather that followed.  It is low-growing, forming small tussocks usually no more than 50cm tall and often much shorter.

The broad leaves are a blue-green with a taper at the top and a fold near the bottom. It is the flowering head though that you will really notice, and which makes the common name self-evident! As you can see from the first photo, the flower head is a short stem with spikes radiating out just like the vanes of a windmill. These spikes are green when young, but darken as it flowers and the seeds mature. There are normally 6-9 of these spikes, and each spike will be covered with seeds that have two wings, or awns. You can just see these in the third photo.

Weed of the Month – May 2016

BURR MEDIC

(Medicago polymorpha)

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(Photos: E. Cousins; habit, closer view of leaves and fruit.)

This small creeping plant from the pea family can be used as a pasture crop, but it can become a weed in some habitats. It is a prostrate (flat to the ground) annual, though it can climb slightly through nearby plants. The multiple stems are green to slightly red, and can be up to 50cm long. The leaves occur in groups of 3 leaflets at the end of short stalks. The centre leaflet has the longest stalk (an identification key used for distinguishing medics from similar plants). Leaflets can be heart or wedge-shaped, as seen above, with finely toothed margins near the tip. Pea-like yellow flowers appear in spring, to be followed by the fruits. These are like little coiled pods, disc or barrel-shaped, 3-4mm wide, with hooked spines (see second photo) all over.

Plant of the Month – May 2016

BUCKBUSH or ROLYPOLY

(Salsola australis)

p1   p2(Photo: E. Cousins, Cape Jervis; plant, close-up of a flower on a ridged stem)

This prickly little flowering annual can grow into a ball about knee high, bright green where a lot of the local plants are a duller colour. The hard stems are really ridged, as seen in the second photo. There you can also see the needle-like tips on the small, cylindrical leaves, making the plant feel spiky. Notice also the papery, cream disk there too? That is a fruit. It has a flattened wing all around, with 5 lobes; the fruit is protected by 3 leaves under it. The plant can break off at ground level and blow away like tumbleweed, dispersing the seeds in the fruit. These seeds then germinate from autumn to winter, with new plants flowering in spring-summer. Earlier called Salsola tragus, buckthorn has been renamed Salsola australis after some detective work by SA Herbarium experts. ‘Salsola’ itself is from the Latin word for ‘salty’.