Mammillaria luethyi

Description: M. luethyi is a very tiny plant, but by far one of the most spectacular members of its genus, distinctive when not in flower because of the 'spination' (if it can be called that!) at the tips of the tubercles, and even more magnificent in flower.
Growth Habits: Solitary or clustering.
Stem: 1.5 cm in diameter.
Spines: Short, soft and white, not prickly.
Origin: Mexico (Northern Coahuila: limestone slabs in Chihuahuan Desert)
Flowers: Large, rich magenta with a white throat.
Lighting: The luethyi needs full sun!!! Poorer luminosity levels produce a green anaesthetic plant with open, far and wide spaced areoles
Watering Needs: Water sparingly, needs good drainage
Cultivation: The plant is often seen grafted, as most of the available stock has so far been propagated this way. Grafted plants grow fast and are very floriferous.
But it is relatively easy to cultivate plants on their own roots and no special care required.
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Cuttings root very well but plants on their own roots are quite slow.

Mammillaria pectinifera

Mammillaria pectinifera (Syn: Solisia pectinata)

The species is classified as endangered because of habitat destruction, grazing of livestock, mining rock for construction, and dumping of rubbish. Actually the illegal extraction and trade of the plant doesn't seem to be a real threat, because artificial propagation is not a problem today, and many nurseries produce the species.

Origin : Mexico

Frost Tolerance: 20°F (-7°C)

Minimum Avg. Temperature: 50°F (10°C)

Sun Exposure: Light shade

Watering Needs: Rot prone, use shallow pot

Propagation: Seeds, or graft

Habitat: Grows in the Tehuacan Valley Matorral, Mexico, a desert/xeric tropical shrub basin, under bushes and other vegetation, on deep alkaline soils with relatively high surface stoniness and high water retention capacity.

The climate is semi-dry, hot, with summer rains and slight temperature oscillations.

Cultivation: Slow growing, this plant is very rot prone and temperamental when cultivated on its own roots, but it is easy to grow if grafted. Mammillaria pectinifera has a fairly large tap root, and should be kept in a deep pot with a very draining mineral substrate.

Watering during the active growing season (spring and summer), this will encourage steady growth. But be careful with watering, which all thick rooted species require (rot sensitive). Keep dry during the winter rest.

Fertilize every 2 weeks with diluted high potassium fertilizer when the plant is in bud. Light shade or full sun exposures.

Propagation: Direct sow after last frost. (seldom produces offsets)

Source: catus-art.biz, www.lithops.net