Endangered plant success!
Photos: E. Cousins, Orobanche flower; C. Schultz, Senecio + Orobanche together in one pot.Note the fine white roots of the host plant filling the pot, and the short fat yellowish roots of Orobanche.
Back from the brink of local extinction? …Perhaps a little dramatic, but a very positive sign for the parasitic plant Orobanche cernua var. australiana (Australian broomrape). SA Seedbank’s website says that the only place it grows in the “Southern Lofty” area is Cape Jervis, with only 15 plants recorded. You may remember from our December 2017 Plant of the Month that we found 100s of plants and collected some seed. This year Liz and I both tried germinating Orobanche seed along with its preferred host Senecio odoratus. Imagine my surprise when, sorting Liz’s excess Senecio seedlings for the COOTS September planting at Land’s End, I found an Orobanche poking its asparagus-like head through the potting mix. Only the one so far and it has been carefully planted on one of the sand dunes at the COOTS site, along with another 4 Senecio seedlings that all have Orobanche seed with them. Fingers crossed that more Orobanche plants germinate, including the ones we planted in June at our coastal display garden near the ferry terminal, and several other locations on our site.
(Photos: E.Cousins; weed growing with other weeds; a stem; close-up of flower head)
Senecios come in many forms … from the rare and unusual to the very common, and from trees through to small weedy herbs such as this one. This groundsel grows to about knee high, with clusters of flower heads at the end of the stems. The individual flowers are only about 1cm long, and don’t seem to open properly, probably because of all those bracts surrounding the petals! Only a millimetre or two of the yellow petals show at the top. There are 15 bracts or more, each tipped with black as can be seen in the 3rd photo above. There are also lots of little bracts at the base of the flower head, again edged in black. Eventually the flower head produces a fluffy white ball, with the seed on the inside of the ball, waiting to be blown away like dandelion seed. Although this weed is found along our coastlines and in our national parks, it is more common in urban areas, or disturbed sites.
(Photos: C. Schultz, sprawling bushes in the foreground; close up of leaves and male flowers)
As their name suggests, saltbushes have a high salt content. They can survive in harsh saline environments. Their ability to survive in a variety of conditions has lead to their becoming part of the diet of many animals…including lamb! Sheep and cattle will graze bladder saltbush readily. This small shrub will grow less than 1 metre tall, but can sprawl. The leaves are quite fleshy unless growing conditions are dry, when leaves might be shed. The grey-green appearance of the oval-shaped, short stemmed leaves is often a give-away for this (and other) saltbushes; leaf margins can be wavy. When you go looking for this one, you will need to look for two versions: the male and the female! The bushes are the same, but the flowers are different. Look for slender but dense spikes of tiny flowers on the newest branches of the male; on the female form, the flowers look more leaf-like, and are about 5mm across.