Wednesday, August 10, 2011

Sundews in the cold

The sundews, or Drosera, are magnificent plants and one of the reasons I got into carnivorous plants to begin with. I first came across them in the early 1990s on a family drive, when my father spotted some from the car and stopped to show us. Interestingly, they were Drosera spathulata var. gympiensis, which was then undescribed.


I don’t grow so many Drosera here in Canberra because not many of them can handle the cold very well. One species that is well adapted is Drosera peltata (although I now suspect I may have put the wrong name on their tag, so they could be D. auriculata). The above photos shows seedlings of the form from the Grampians in Victoria. They have handled temperatures down to –8*C without significant losses. As they self-pollinate, I’m hoping they will become a weed for me in the same way that D. capensis is a weed for most other people. Here is one of the more advanced seedlings which is quickly putting up its climbing stem. This photo was taken a week after a –8*C frost that reached to the top of 30 meter gum trees and gave Canberra white out conditions with an air frost, so they are quite resilient.


Drosera capensis was indeed a weed for me in Queensland also, but now I might have 3 or 4 plants at most – I went on an eradication drive for the few stragglers after I brought some D. binata with sundew bugs (Setocoris) living on them. One clone that I want to keep is a giant form that my friend David Martin grew in Queensland. I’ll wait for it to recover and put on some good foliage before I post photos of it.


Another native Drosera that is doing well for me is Drosera pygmaea “Kangaroo Island” ex Triffiod Park. These plants are close to ones I photographed down at Tathra earlier this year. Despite the freezing cold here, they are already putting up flower buds and new leaves. They are great at dividing and conquering, as they produce clones or plantlets from green propagules called gemmae. Here is a close-up of some D. pygmaea gemmae (the green seed-like things in the center of the photo). When they get hit by a drop of rain, they literally spring from the plant and get splashed around into the soil. If they land in a good spot, they will grow. I give my plants a helping hand by using the pointy tip of a plant label or a skewer to flick them around nearby pots.


Wild D. pygmaea can form incredibly dense populations. The ones I found at Tathra were growing in a really limited area, no more than a few square meters. But there were still hundreds (if not thousands) of them. See if you can count how many are in this photo (which shows an area maybe 20 x 20 cm in size of the Tathra population).


Plantlets are growing right now from gemmae I sowed back in May (although they have a good way to go yet).


Another pygmy Drosera that is doing well for me is Drosera palaecea. I only have a few, because a falling greenhouse tray killed all but one of my plants. Fortunately, I have a few gemmae plantlets coming on, including this one:


Of the non-indigenous Drosera, the best adapted to our frigid winters is a clone of Drosera rotundifolia from Lake Wohink, Oregon. I had tried this species a few years back with no luck, but some plants Ron Abernethy weeded for me from his Darlingtonia have done really well. Unlike our Australian Drosera which either grow in winter or year around, these D. rotundifolia retreat to winter resting buds that look like this:


Drosera rotundifolia flowered and set seed for me last season, so I am hoping to see some seedlings in the Darlingtonia trays. This year, I will probably seed them into my Sarracenia as well for a bit of extra interest. I also grow a few clones of Drosera binata, but they are all well and truly dormant now and not at all photogenic.

Plants that have not done well for me here include: Drosera regia (died outright in –6*C), Drosera hamiltonii, Drosera burmannii, Drosera aliceae, Drosera nidiformis and Drosera capensis. The latter plants will grow, but never thrive to the extent they do in a frost free area. Even D. capensis dropped to so few plants that I could eradicate almost all of them in 10 minutes of weeding. One plant I do not grow (and probably should!) is the Drosera peltata from Tuggeranong. Well, everyone else grows it – given I live within walking distance of it, so should I!