Thursday, October 24, 2019

Stinking milkweeds - excellent succulent houseplants!

Celebrating our upcoming talk on succulents by Barry Parker, here is one of the more unusual succulents in the milkweed family. Stapelia is an African genus of leafless succulents from near-desert regions. The swollen stems look a bit like cacti, although there is no relationship.
Stapelia grandiflora stem and bud. Clement Kent, CC-by-SA 4.0

These beauties spend the winter in my kitchen window, as they won't tolerate temperatures below about 10C/50F. Most importantly, in winter they need to be kept almost bone dry. I water them perhaps once a month between November and May, and only very sparingly.

view of bud from above. Clement Kent, CC by SA 4.0
All of this changes when they go outside after it's warm enough. I give them a week in partial shade to prevent sun scorch, then move them to the sunniest part of my porch. Then I begin a regular program of watering with occasional infusions of soluble fertilizer. By July or August I'm greeted by the huge buds, about 3" wide by 4" long.

Several days will pass as the buds grow, and grow, and grow. Finally, one morning before I'm up, they will open.

When this happens, there's a treat for many senses. The nearly foot-wide blooms are a rich golden-orange with dark purplish-red stripes. The hue deepens to the same red meat color at the center of the flower, where elaborate floral parts sit.

freshly opened Stapelia flower, 10" wide. Clement Kent, CC by SA 4.0

The flower is densely covered in long hairs or cilia. Brush them with your fingers - some say it feels like fur.
Stapelia grandiflora closeup showing hairs. Clement Kent, CC-by-SA 4.0
 So far we have sight and touch covered. Take the next step: get close to the flower and take a whiff.

Phew!!! smells like rotting meat!  You've just discovered the most powerful lure in this flower's pollination bouquet. It looks and smells like a rotting carcass, to attract its pollinator: carrion flies.

Let's look again at the center of the flower. See the white egg clusters? They are from the greenbottle fly, one of the first flesh-feeder to arrive at dead animals in the wild.
greenbottle fly eggs on Stapelia - Clement Kent, CC-by-SA 4.0

Click on the video below to see the hatched eggs - a.k.a maggots - waving in the breeze as they try to find the yummy dead meat. Mama greenbottle makes a flying visit.

If you sit and watch your flower for a bit longer, you'll see other visitors.

If you should be lucky enough to have two flowers open at the same time, and the flies carry the pollinia (specialized pollen clusters) from one to another, then you'll eventually see a very milkweed-like seed pod develop, and open to reveal seeds with fluffy appendages to help them fly.

If you want to share with friends, or just have more for yourself, use a clean knife to cut one of the stems (or just snap it in half). Don't get the white sap on your skin - it is irritating. Let the detached stem sit in an airy, dry, sunny place for several days to heal. Then plant it in very free draining material, like you would use for a cactus (gravel is good). Don't water more than once every few weeks until you see signs of new growth. 

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