Asclepiads


Dregeas come from Asia and are evergreen in the wild, but if you keep them in your greenhouse with low winter temperatures, they will lose most of their leaves. They are also known under their synonym Wattakaka sinensis.
It is a climbing plant that will flower every spring with white flowers that have a splash of pink in the centre. They are highly scented, which usually means in these type of plants that they are moth-pollinated. The flowers last for up to a week and resemble hoya flowers. Not surprising as Hoyas and Dregeas are related. Another asclepiad species that has highly scented moth-pollinated flowers is Araujia sericifera, although the flowers on that plants do not resemble Dregea flowers.

Dregea sinensis

Dregea sinensis

As with Hoyas, Dregeas rarely set seed in the greenhouse, but when they do, they form twin-seed horns which will burst open when ripe and can contain up to 50 seeds. The seeds remain viable for up to a year, but it is better to sow them as soon as possible. If you sow them straight away, you will get almost 100% success; if you leave it till 3-6 months, you will get 25-50%; and after a year, you may only get one or two to germinate.
The leaves are heart-shaped and fairly large. It is possible to propagate this plant by cuttings, preferably in the spring. I use cuttings with two nodes, one for the roots and one for the new growth, just as you would do with Hoyas. They can be grown in shade or full sun and will grow outside in the summer. They can have a bit of frost (-2 or 3°C), but it is better to give them some protection.

This very rare Asclepiad and one of only two endemic species from the Dhofar region of Oman, the other being a Dhofaria macleishii (of the Capparaceae family). It is extremely drought tolerant and slow growing. It is an ideal plant for a small collection as it grows very slowly. I have had mine for about 3-4 years now and it has only grown by 4 centimeters in that period. Not suprisingly, it does appreciate warm temperatures, at least 20°C. Despite the fact that it grows in the full sun in the wild, my experience with this plant has shown that it can be grown in the shade without any problem.

It will also flower well, producing up to ten flowers successively in October-November. The flowers are about half a centimeter in diameter and stay open for two or three days. On my plant, they are produced on the new growth at the end of the stem, but in older plants with more growth, they grow in the leaf axils. You can see a picture of a dried specimen here. The few leaves the plant produces at the end of the stem, drop off before the flowers appear. The leaves you see growing in the picture are from a different plant, a Dorstenia foetida.

The plant was named Cibirhiza dhofarensis by Peter Bruyns, but is also known as Cibirhiza dhofarica. Cibirhizas are closely related to Fockea, a well-known species of that genus being Fockea edulis. The tuber of the Cibirhiza is supposed to be edible, but I have not tried it, because I only have one plant and it would be a shame to destroy it.

Cibirhiza dhofarensis

Cibirhiza dhofarensis


Cibirhiza dhofarensis

Cibirhiza dhofarensis

A strange name for a strange plant, even stranger is the other name it is known by, namely: Spathulopetalum dicupuae; I will stick to Caralluma. It has a different growth to what one normally associates with Stapelias: when they are going to flower, the stems elongate producing flowers along the extended growth. These elongated parts can be anything between 14 and 20 cm long and the flower lobes themselves are 2 cm long. There are about 15 species of this type of Caralluma found in Eastern Africa and one or two in India.
The plant comes from eastern Kenya around Archers post which is north of Isiolo. This is a very dry part of the country with only sporadic rainfall. It is also a very hot area, therefore the plant in cultivation must be kept at a high temperature all the year round, at least 15° C, but preferably warmer. Because it requires such high temperatures, it is a rare Stapeliad in cultivation. It can be grown in the full sun where it will get the red-mottling on the stems, otherwise it will remain green. They require very little water throughout the year, so it is best to use a very open compost with plenty of grit.

Caralluma dicapuae Archers post

Caralluma dicapuae Archers post

This plant is also known as Stultitia conjuncta, but in 1978 it was moved to Orbeanthus. Recently, Peter Bruyns, one of the top Stapelia people, has placed it in Orbea, but there is a lot of movement in the naming of Stapelias, so it is entirely possible that it will be moved back to Orbeanthus. This genus contains only two species; the other one being Orbeanthus hardyi.
It is not a common plant in cultivation, but is very suitable for a hanging pot; the stems can grow up to 50 cm in length and are greyish green mottled with darker green. The flowers are cup-shaped and look similar to those of Hoya archboldiana, the colour being white with a red centre. The flowers are produced singly or in pairs, mainly in the summer.
It requires a well-drained soil, preferably mixed with grit. Propagation is by seed or cuttings. Cuttings need to dry for a couple of days before being put in the soil to avoid rot, as is the case with most succulents. Bottom-heat is preferred to speed up rooting. The plants can be grown either in full sun or shade, but you will get more mottling on the stem if they are kept in the sun.

Orbeanthus conjunctus

Orbeanthus conjunctus

This tropical asclepiad originates from South-America and is now widespread in most (sub-)tropical regions of the world, such as Spain. It is both drought-tolerant and the opposite; it can take plenty of rain. It is a climbing plant that can grow to up to 5-10 metres high. In some countries it is now considered to be a weed, but it is nevertheless a highly ornamental plant, producing pink-striped white flowered. The flowers are scented all day, unlike some asclepiads, among them some hoyas for instance, which are only scented at night. The plants are mainly moth-pollinated, certainly in their country in origin, but in other countries where they have established and the correct type of moth is not present, the pollination is done by bees. Araujias are known as the cruel plant, because if the wrong type of moth (i.e. too small a moth) tries to pollinate the flower, its tongue will get stuck in the pollination system, and unable to escape, it will die. Bees and larger moths do not get stuck because they are heavy enough to pull free. Seedpods produce up to a few hundred seeds per pod. The seed is carried on the wind by small parachutes, similar to thistles.
Araujias are close relatives of the Dregea from China, of the Periploca from the Mediterranean and of the Stephanotis from Madagascar and are very easy to grow as houseplants, being able to grow in shade or sun, and not fussy as regards soil. The only limiting factor is frost. The flowering period is summer. Propagation is mainly from seed, but cuttings are also possible.

Araujia sericifera

Araujia sericifera


Araujia sericifera

Araujia sericifera

This is a very popular plant in cultivation, because it is very easy to grow and flowers regularly throughout the year with cream-coloured flowers. The flowers are highly scented to attract moths for pollination. It is a suitable plant for hanging baskets where it will grow to 1-2 metres. It can also be grown on a trellis, but it has to be fastened up. It can best be grown in half shade, but it will tolerate some sun. Lacunosa has many variations in leaves and flowers and hence a lot of cultivar names are used for the same species.
The plant originally comes from Java, Malaysia and Thailand and therefore likes a lot of warmth (at least 20°C) to do well. It does well in the ordinary living room as long as you keep it well-watered. It is very easy to propagate from cuttings and also by seed as long as moths have access to the plant.

Hoya lacunosa

Hoya lacunosa

There are two variations of Dischidia nummularia; one a plain green one, the other with variegated leaves. The green form flowers a lot easier with small white flowers. Dischidias are very closely related to Hoyas, so much so, that a number of species cannot be told apart until they flower. Dischidia nummularia variegata is a good example; it was a few year before it flowered and I could work out what it was. And for one or two species of Dischidia, even when they flower, the experts cannot determine – or do not agree – whether they belong to the dischidias or to the hoyas.
Dischidia nummularia comes from South-East Asia and is an epiphyte, growing on the tree trunks. Because the flowers are small and often appear well above head height, they are difficult to spot. It likes plenty of light to grow well and if you are lucky you will get flowers, but it may take a while. It is an untidy grower and likes plenty of space. The plants can be grown in either a compost mixture or on a piece of bark or similar medium. Generally speaking, dischidias prefer a higher temperature than hoyas, but these two grow quite well in the same temperatures as hoyas. Both are very easy to propagate by cuttings and will, in summer, root in about six weeks.

 

Dischidia nummularia variegata GPS 10249

Dischidia nummularia variegata GPS 10249

Dischidia nummularia GPS 10245

Dischidia nummularia GPS 10245

This is a very easy species to grow, just as easy as Ceropegia woodii. It is a trailing variety which will sometimes climb; it will grow very long, but do not be tempted to cut it back or you will lose the flowers. The flowers will appears when the plant has reached a length of about 1.50 metre. The flowers are about 2cm long and do not stand out. The leaves are long and thin, hence the name linearis. If you grow a stem horizontally, for instance on a potting table, the nodes will send out roots if they touch the soil. This is an easy way of propagating the plant, which is useful as linearis seed is rarely produced.

It is a tuberous-rooted species and the tubers will form from cuttings, as is true of all tuberous-rooted ceropegias. It will grow in most soils and requires only a little bit of heat (5-10°C) in the winter. In the summer, it prefers to be grown in a shady place, but temperatures can be quite high without any problem.

Ceropegia linearis

Ceropegia linearis

This species originates from Kenya and is very similar to C. robynsiana and C. evelynae, but is easier to grow and will tolerate lower temperatures and humidity. It grows in its natural habitat on sheltered river banks and in wooded valleys. One of the places it can be found is the Meri river near Mount Kenya and another is the Teita Hills near Voi. Voi, by the way, is where a number of species of Ceropegia can be found, such as C. solomensis and various nilotica types.
The plant will get very large, producing growth up to 3 meters in length. Only when it has reached a certain length will it flower. This is a common feature in a number of rampant species and it is therefore advisable not to cut back the shoots or no flowers will appear. The colour of the flower tips can vary slightly, from pale yellowy green through to red and the stems can reach a diameter of 2.5 to 3 cm at the base. Unlike most other ceropegias, this species will flower on the peduncles from the previous year.

 

Ceropegia succulenta

Ceropegia succulenta


Ceropegia succulenta

Ceropegia succulenta

Ceropegia rupicola comes from Yemen; Ceropegia aristolochioides comes from an area between Senegal and East-Africa, in other words, from the tropical area just south of the Sahara. Normally these two species do not come into contact with each other, but in collections this is quite possible and this is what happened. The result is the cross of which you see the flower in the picture below.
The flower and stem are similar in structure to that of C. aristolochioides, but it is much larger. Barring the difference in size, the plant could easily be mistaken for an aristolochioides, but for the fact that the seeds were definitely collected from a rupicola plant. One of the reasons that there are not more hybrids from these two species, unlike for instance C. sandersonii and C. stapeliiformis which produce many hybrids, is because rupicola is difficult to keep in cultivation and you need to have a large plant before it flowers.
The C. rupicola x aristolochioides prefers conditions more like those in the natural habitat of C. aristolochioides, that is: hot and moist, rather than the dry heat in which C. rupicola grows. It can take drier conditions, but then it will not grow so very fast. In cultivation, it can also take cooler conditions, down to 15°C, but it does a lot better when it is kept warmer.

 

Ceropegia rupicola x aristolochioides

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