A.k.a. Bird's nest Mammillaria, this is a wonderful old favourite cultivar with curly golden-yellow spines. A plant soon forming many heads. The new growth is very attractive, the long, entwining yellowish spines soon form a mat. A real beauty. 

Family: Cactaceae (Cactus Family)

Scientific name:  Mammillaria camptotricha 
cv. marnier-lapostollei   (forma curvispina)

Origin:  Garden origin (Nursery produced cultivar)

Common English Names include: Bird's Nest Cactus

Etymology: Named to honour Anne Therese Marnier-Lapostelle, the first wife of Julien Marnier-Lapostolle - owner of famous plants collection "Jardin Botanique des Cedres" in Cap Ferrat (France). President of "Association Francaise des Amateurs de Cactees"

Conservation status: Listed in CITES appendix 2.

Synonyms:

• Dolichothele marnier-lapostollei
• Mammillaria marnier-lapostollei
• Mammillaria camptotricha cv. MarnierLaPostollii n.n.
• Mammillaria camptotricha var. delapostella n.n.
• Mammillaria camptotricha "le marnier"
• Mammillaria camptotricha 'Madam Marnier'
• Mammillaria decipiens ssp. camptotricha 'Mme. Marnier'.n.n.
• Mammillaria camptotricha "curvispina" (= curlispina)

Mammillaria camptotricha cv. MARNIER-LAPOSTOLLE.
A.k.a. Bird's nest Mammillaria, this is a wonderful old favourite cultivar with curly golden-yellow spines. A plant soon forming many heads. The new growth is very attractive, the long, entwining yellowish spines soon form a mat. A real beauty. 

Description: M. decipiens (including M. camptotricha) is a small plant that make a large, flattish clump of stems clustering from the lower part.
Stem: Individual stems bout 4 - 7 cm in diameter, up to 10 cm tall, broadly globose to club shaped, depressed, deep-green.
Roots: Very large, tuberose.
Tubercle: Green, soft, flabby, cylindrical to obtuse about 2 cm long. Without latex. The axil is sparsely hairy with a few bristles.
Radial spine: Usually 4 - 5, but varying from 2 to 11, 7 to 30 mm long, thin, needle-like, flexible, (sometime bristly and twisted) curling, yellow, or white, sometime brown tipped, interlacing densely in full light.
Central spine: Absent. Or 1 to 2, slender needle like straight, brownish about 18-27 mm long.
Flower: Funnel-form, delicately scented, mall, white, deeply set in the tubercles, to about 1.5-1.8 cm long and wide. The outer petals of the flowers are greenish.
Fruit: Cylindrical, pale pink to greenish.
Seed: Light brown.

Three subspecies are recognized by some authors:

• subsp. decipiens with 5-11 withish radial spines. Origin: San Luis Potosi, Guanajuato and Queretaro
• subsp. albescens with 3-5 short radial spines straiter and white. Origin: Guanajuato and Queretaro
• subsp. camptotricha with 4-5 bristly yellow radial spines up to 30 mm long Origin: Queretaro

M. camptotricha has two nice cultivars:

• cv. Marnier-Lapostollei (a.k.a. 'Madam Marnier') It is a a distinctive clone with pale green body that bears very short reddish tipped tubercles (10-12 mm long ) and tightly strongly curved or twisting  gold spines only 6-9 mm long. The flower is small and white.
• cv. Bru (a.k.a forma brevispina) with pale green body with 4 to 5 very short golden radial spines.

Cultivation: This plant is easy to cultivate in a well drained and mineral substratum and avoid the use of peat or other humus sources in the potting mixture. Pot plants are quite wet-sensitively, especially in light of its small root system (Do not over-water). Water regularly during the growing season, let soil dry in between to prevent root rot, keep dry in winter.   It need medium sun exposure. Usually it is recommended to overwinter this plant in a bright and warm greenhouse with at least 8-10° C , but it proved to be quite frost resistant (if kept dry it hardy as low as -7° C) A resting period in winter and strong light are necessary so that it can flower properly. Plants will offset readily, and dense clumps can be produced in a very few years. Feed with a high potassium fertilizer  in summer.

Propagation: Through cuttings.