Asclepias physocarpa (E. Mey.) Schltr.1896, commonly called Balloonplant, Balloon Cotton-Bush, Swan Plant, Oscar, Hairy Balls or Giant Swan Milkweed is an exotic, undershrub perennial herb, native to the South of Africa, but nowadays widely distributed in tropical and subtropical regions around the world. As we saw the balloonplant in flower for the very first time, we thought it must be at least a relative to Hoya plants. We´ve been right. Like Hoyas, the Balloonplant (Asclepias physocarpa) belongs to the dogbane family (Apocynaceae) and further on to the milkweed subfamily Asclepiadoideae. The Hoya-like flowers get a size of about 1 cm in diameter. Flowering period: Summer. The tropical plant reaches hights of more than two meters and carries a poisonous, milky sap.

All parts of the plant are toxic !
Because of its poisonous sap the Balloonplant is very attractive to butterfly caterpillars, especially Monarch butterfly caterpillars (Danaus chrysippus), using the leaves as food. Our large plant has been killed by this caterpillars within 3 weeks. The extraordinary and quite large tropical plant requires warm - hot temperatures, a well-drained soil and full sun.
The balloon-like, hairy fruits last several weeks and are used for exotic flower bouquets and floral decorations. The Balloonplant is also known under the botanical name Gomphocarpus physocarpus E. Mey. 1838, which is just accepted as a synonym.

Flower Photography © Orchids Flowers.com
Image: Balloonplant flowers (Asclepias physocarpa)

Flower Photography © Orchids Flowers.com
Image: Balloonplant fruits (Asclepias physocarpa)