Food fit for Monarchs
Balloon milkweed is important for butterflies,
THIS has not been a particularly hot summer which, for most of us, has been a blessing. I was chatting recently to well-known botanist Elsa Pooley, who mentioned how the summer never really got off the ground.
She said plants she had installed in gardens in spring took a lot longer to grow than in previous seasons. It shows you how rains and temperatures are so critical in the growing season for plants and gardens.
We move in to autumn, my favourite time of the year. In the Upper Highway area there is so much colour with many of the exotic flowering trees in full bloom.
My garden has had a very late flowering of the African Dog Rose, Xylotheca kraussiana with it full of the red Acraea butterfly caterpillars which will soon burst out of their pupae state and produce beautiful butterflies.
Another tree that has flowered well in the past three weeks has been the forest Gardenia, Gardenia thunbergia.
Sadly it flowers only for a few days under ideal conditions but in that period gives so much joy to us gardeners.
Many shrubs are also in flower with particular emphasis on Plectranthus ecklonii, large spur flower and
Bauhinia galpinii, Pride of de Kaap.
The plant I would like to discuss this month is one many think is a weed.
On the contrary, this is one of the most important plants for butterflies, found growing throughout the coastal regions of our province. Gomphocarpus physocarpus or better known as balloon milkweed, balloon wild cotton and hairy balls, belongs to the family Apocynaceae.
It is widespread in South Africa, occurring in the Western Cape, Eastern Cape, KwaZulu-Natal, Mpumalanga, Gauteng, Limpopo and North West. It is mostly found in grassland and bushveld, often along roadsides and in disturbed areas, from the coast to 900m above sea level.
The genus Gomphocarpus is derived from the Greek
gomphos meaning a club, and karpos, fruit. The specific name, physocarpa, is derived from the Greek physa meaning bladder and karpos, fruit, referring to the inflated, bladder-like fruits.
The genus Gomphocarpus comprises 25 to 32 species that occur in Africa and the Arabian Peninsula. Ten species occur in southern Africa. Gomphocarpus physocarpus is an upright, soft shrub which grows to about 2m, with a fibrous root system. Its branches arise above a small, single-stemmed trunk which are pale yellowish green and hollow. The leaves are light green, opposite and lanceshaped. The creamy white flowers hang in pendulous bunches throughout the year, but mainly during summer (November to April).
Flowers are followed by large spherical inflated fruits covered with soft spines, splitting to release many seeds, each with a tuft of long silky hairs attached at one end, thus wind dispersed. It is an excellent butterfly plant, but sadly very poisonous if ingested by humans and livestock. When leaves or branches are broken, the plant exudes a milky white latex that is poisonous if ingested.
Pollination of
Gomphocarpus physocarpus is highly specialised. It usually involves trapping the leg or proboscis of the pollinator so that the pollinia get attached to it, and then a similar process, in the next flower visited, to trap the insect again but this time to remove the pollinia. Gomphocarpus physocarpus is self-incompatible (that is, it cannot set seed unless it receives pollen from a different plant).
It is a food plant for the larva of the African monarch butterfly (Danaus chrysippus
orientis). Luckily the caterpillars are immune to the poisonous milky sap which is stored and then passed onto the pupa and the butterflies. The caterpillars are foul-tasting and poisonous to predators. If you visit the Muthi Market in Durban, you will find the plant is used extensively for traditional medicine, the roots to treat stomach ache; leaves dried and ground into a powder taken as snuff; and the milky latex to treat warts.
The inflated fruits are used in flower arranging because they last well when dried.
Once you have a plant in your garden it will produce lots of fruit and seed in late summer. It is a quickgrowing shrub that is sadly short lived.
Grow this plant in a welldrained sandy soil in full sun. It is easily propagated by seed, sown in spring or summer. To harvest the seed, allow the fruits to ripen on the plant and harvest as they start to split open. Keep a close eye on them or bag them, because once the pod splits open, the seeds disperse in the wind. Gomphocarpus physocarpus always adds interest to your garden, especially in herbaceous borders.
Plant them in full sun and in an area that can be seen as the large round fruits are a feature that creates an interesting texture to your landscape.
Please make sure the plants are kept away from the house and reach of children as the milky latex is poisonous. PLANTS IN FLOWER IN MARCH: Enjoy the group of plants under the Genus Plectranthus, in particular Plectranthus ecklonii, zuluensis and ciliatus which are in full bloom.
If you drive around the greater Durban area, the one that stands out are the three colour forms of Plectranthus
ecklonii which are large shrubs of pink, white and purple. It is a rewarding shrub that flowers in March for about 3 to 4 weeks and which requires little maintenance except after it has finished flowering when you need to cut it back. Its common name is the large spur flower.
Strelitzia reginae, Bird of Paradise. We have the two colour forms.
The more common orange flower and then the yellow form known as Mandela’s Gold. The leaves are used extensively by flower arrangers.
The flowers stand above the foliage at the tips of long stalks.
They are also great bird attractants especially when in flower. Sunbirds in particular sit and drink the nectar which forces the petals to open and cover their feet in pollen.
Tulbaghia violaceae, wild garlic. A popular plant useful for difficult hot corners of the garden because it will tolerate prolonged drought, although it flourishes with regular watering.
The pinkish-mauve tubular flowers, clustered into umbels of up to 20 flowers, are held above the leaves on a tall flower stalk, and appear over a long period in summer (January to April). Asystasia gangetica, Creeping Foxglove.
This is an attractive, fast-growing, spreading, herbaceous groundcover that grows from 300mm to 600mm in height. It produces a creamcoloured flower with purple markings on the lip.
It can be used as a mass planting under large trees and borders in full sun, semishade or full shade. It is also the food plant for the Blue Pansy butterfly.