Accepted Scientific Name: Piaranthus geminatus (Masson) N.E.Br.
J. Linn. Soc., Bot. 17: 163. 1878 [1880 publ. 1878]
Piaranthus globosus Photo by: Valentino Vallicelli
Nice and quite popular plant in collections, because of its ease of growth and unusual appearance. The name is due to the stem segments that are ovoid or globose, light green and resemble a mass of tiny potatoes.
Origin and Habitat: Eastern and Western Cape Provinces (Little Karoo)
Synonyms:
See all synonyms of Piaranthus geminatus
Description: Piaranthus globosusSN|18033]]SN|18037]] is a clumping and prostrate species that spread over the ground forming large cushions. The name is due to the stem segments that are ovoid or globose, light green and resemble a mass of tiny potatoes.
Stems: Procumbent or ascending, divided in short squat ovoid or cylindrical articles obtuse to obscurely 4-angled, with 2-4 minute teeth along each angle. Surface smooth or slightly rough, light-green, tips faintly purple.
Flowers: 1 to 2 (rarely more) in a short inflorescence at the stem apex. Flowers are Valerian scented with fruity component about 1,3 to 2 cm in diameter, star-shaped, flat, more or less pubescent, and velvety whitish, yellowish with or (usually) without brown-red dots or transverse lines. Peduncles 2-20 mm long x 1-2 mm in diameter, sepals 2-4 mm long.
Blooming season: Produces numerous flowers simultaneously in October.
Taxonomy remarks: The genus Piaranthus is a very confusing complex of extremely nearly related species with many intermediary forms growing together in many widespread localities and they are very difficult to distinguish. Also experienced botanist found difficulty to separate and classify reliably the various species and forms.
In particular Piaranthus geminatusSN|18032]]SN|18024]] var. geminatus is a very variable species which now also includes the former species Piaranthus globosusSN|18037]]SN|18037]], Piaranthus disparilisSN|18024]]SN|18032]], and Piaranthus pillansiiSN|18037]]SN|18033]].
Subspecies, varieties, forms and cultivars of plants belonging to the Piaranthus geminatus group
- Piaranthus barrydalensis Meve: flowers whitish to yellowish with brown-red dots or transverse lines margin recurved. Corona yellow, and red. Distribution: Barrydale in the Little Karoo
- Piaranthus disparilis N.E.Br.: has smaller corolla-lobes and different markings on the corolla. The crest of the corona-lobes is distinctly toothed, not merely minutely tuberculate. Distribution: Cape Province (Central region Laingsburg Div.)
- Piaranthus geminatus (Masson) N.E.Br.: Flowers 13-42 mm in diameter, star-shaped, more or less pubescent, whitish, yellowish, reddish or bright brown, with or without brown-red dots or transverse lines. Corona yellow, unspotted.
- Piaranthus geminatus subs. decorus (Masson) Bruyns: flowers green-yellow with dark red-brown, patches or bands and densely velvety-hairy. inner corona lobes incumbent on the anthers with large and deeply furrowed crests. Distribution: Northern Cape, Western Cape.
- Piaranthus geminatus var. foetidus (N.E.Br.) Meve: Flowers 18 mm to 30 mm in diameter, star-shaped, pubescent, and velvety ivory, to sand coloured, with brown-red dots or transverse lines. Corona yellow to orange.
- Piaranthus globosus A.C.White & B.Sloane: The name is due to the stem segments that are ovoid or globose, light green and resemble a mass of tiny potatoes.
- Piaranthus pillansii N.E.Br.: flowers 3-4 cm wide, typically greenish yellow, pale yellow or very pale-reddish, without (or with very fine) red spots. Corona yellowish-green.
- Piaranthus pillansii var. fuscatus N.E.Br.: lobes broad, lanceolate, acuminate, dark purple (or dark crimson?) with very numerous slender irregular transverse and labyrinthine greenish-yellow lines and markings.
- Piaranthus pillansii var. incostans N.E.Br.: lobes densely dotted or transversely marked with light purple on an ochreous ground, sometimes so minutely as to look light pinkish-brown.
Notes: Pollination:
These plants are pollinated by flies (myiophilous pollination). Fly are attracted by olfactory stimuli, imitating dung or decaying organic (zoogenic or phytogenic) matter, together with mimetic colouration and, sometimes mimetic sculpturing. Nectar is present. The nectar mainly serves as optical attractant causing brilliance effects, and as visitor guide. However, nectar obviously is also a reward. In the pollination process flies carry pollinaria only at the distal parts of their proboscis, never on their legs. The pollinator spectra are similiar between of flowers in habitat and cultivated ones.
Bibliography: Major references and further lectures
1) Werner Rauh “The Wonderful World of Succulents: Cultivation and Description of Selected Succulent Plants Other Than Cacti” Smithsonian Institution Press, 1984
2) Hermann Jacobsen “A handbook of succulent plants: descriptions, synonyms, and cultural details for succulents other than Cactaceae” Volume 1 Blandford Press, 1960
3) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/ago/2011
4) Doreen Court “Succulent Flora of Southern Africa” CRC Press, 01/giu/2000
8) Focke Albers, Ulrich Meve "Illustrated Handbook of Succulent Plants: Asclepiadaceae: Asclepiadaceae," Volume 4 Springer, 2002
9) Alain Campbell White, Boyd L. Sloane "The Stapelieae: an introduction to the study of this tribe of Asclepiadaceae" S. E. Haselton, printer, 1933
10) John Robert Brown "Unusual Plants: 110 Spectacular Photographs of Succulents" Abbey Garden Press, 1954
Piaranthus globosus Photo by: Giuseppe Distefano Piaranthus globosus Photo by: Cactus Art Piaranthus globosus Photo by: Valentino Vallicelli Piaranthus globosus Photo by: Cactus Art Piaranthus globosus Photo by: Giuseppe Distefano Piaranthus globosus Photo by: Cactus Art Piaranthus globosus Photo by: Valentino Vallicelli Piaranthus globosus Photo by: Valentino Vallicelli Cultivation and Propagation: It is an easy blooming plant when mature that require moderately watering through the growing season but enjoy plenty of water and some fertiliser in hot weather, this helps them to flower freely. Water more sparingly in winter according to temperatures. But, as with most asclepiads, it is unwise to leave them wet in cold weather. Winter care presents no problems at 5°C with plenty of light. Since roots are quite shallow, use a cactus mix or add extra perlite or pumice to regular soil potting soil. A gritty, very free-draining compost is suitable, and clay pots help the plants to dry out between watering.
Sun Exposure: Partial sun or light shade
Pest and diseases: Stapelia species vary in their susceptibility to rotting, but are generally fairly easy to grow, especially if kept pest-free. They are very susceptible to stem and root mealy bugs, and damage from these may well initiate fungal attack. If you do have problems with a stem or with basal rotting, you can reliably isolate the healthy parts, dry them off, and re-root them in moist compost.
Cultural Practices: Re-pot every 2 years
Propagation: Easiest with stem cuttings. Allow cuttings to dry a day before planting. Stems must be laid (Not buried) on gritty compost and will then root from the underside of the stems. It can also be increased from seeds sowing in spring in moist, sandy peat moss.
Potting medium: Since roots are quite shallow, use a cactus mix or add extra perlite or pumice to regular soil potting soil. A gritty, very free-draining compost is suitable, and clay pots help the plants to dry out between watering.
Your Photos
by Valentino Vallicelli
by Valentino Vallicelli
by Cactus Art