Opuntia polyacantha

Opuntia polyacantha is a common species in colder places of American West. It often found in higher elevations and spreads far north.
The plant in picture comes from near Utah-Nevada border, not far from Great Basin NP. Here in Bay Area this form does well grown outside year long, stays compact and apparently a proliferous bloomer.

Echinocereus mojavensis

Here are 'ripe' about to open buds of E. mojavensis. Developing buds are as much fun to watch as there are flowers, and they stay around longer.
Here you can see clearly the distinct for this group of Echinocerei bud areoles with crab-like spread spines. The red claw-like forms covering areoles are actually true leafs.

Notocactus herteri

A pink flush from N. herteri comes every spring. This is the light colored specimen, of the two I have.  Each produces about 50 flowers over couple of weeks.

Austrocylindropuntia shaferi

These are 6 months old seedlings of Austrocylindropuntia shaferi, very robust and quickly growing plants, by far the largest cactus seedlings of that age I've ever seen.
Austrocylindropuntia shaferi is an Argentinian cholla, forming low very spiny bushes with nice red flowers. The seedlings demonstrate well pronounced leaves, a distinct feature of several Austrocylindropuntias.

Rebutia pygmaea

Here is another flower color variation from amazing Rebutia pygmaea clan. This species of small plants with thick taproot should properly belong to old genus Meidlobivia and famous mainly for it's flowers, produced freely but unfortunately only in the spring.

Sulcorebutia tarabucoensis

Sulcorebutia tarabucoensis v. callecallensis VZ 56b is how it spelled in my records. Yet another Sulcorebutia with beautiful bi-colored flowers. 

Oreocereus leucontichus

This name is synonym to O.hendriksenianus, just a different form. The plants have nice yellow or sometimes red spines and pretty 'hair'.
By some reason hair-like spines on cacti are often associated with cold protection, when in reality they serve much more important role, assisting in moisture collection. In areas with regular fog thin hair-like spines collect tiny droplets of water from air, making it accumulate at the plant base, were it eventually gets to it's roots.

Echinocereus mojavensis

Wide-spread in SW USA species, E. mojavensis usually has orange-pink flowers, but some populations in N. Arizona display this pink-red shade. The species is common in nature, but not in collections, despite ease of growing and nice flowers.

Echinocereus papillosus

Echinocereus papillosus is a small prostate plant, but it's flowers are amazing - among largest in the genus. Definitely a must have in every cactus collection, space permitting.

Echinocereus cocinneus hybrid

This spring E. cocinneus hybrid opened three flowers, up from only one last year. This is a female plant, with no pollen produces, but fertile stigma. Cross-pollination it with another cocinneus hybrids seems like a natural thing to do.

Eriosyce senilis

This is another fairly common plant now days, often available in garden centers. That does not make it less interesting. The plant is covered with stiff curly hear-like spines, usually white but often with black tips.

Echinocereus parkeri

E. parkeri is one of the smaller clumping Echinocerei, forming low bushes. It is generally uncommon species in collections, easy to grow and ready flowering. Finger-thin stems protected by 2 inch/5cm long straight spines.

Rebutia violaciflora

An old classic, even if merely a form of R.minuscula, known for it's special flower color. The flower color slightly varies from season to season, this year it is a bit more reddish.

Turbinicarpus pseudomacrochele

Turbinicarpus is the genus of many small plants, favored among hobbyists. Plants are blooming reliably from 2 years of age if not younger, and very non-demanding in care. Flowers are often pink, but also white and yellow.

Note the very different adult and juvenile spines on the main plant stem and on the offsets at the picture bottom. Not all but many cacti have such differentiation in spines.

Echinocereus pulchellus

Echinocereus pulchellus is always favored by hobbyists for both compact growth and spectacular flowers. It is easy plant, available from specialized nurseries, and can easily grown from seeds with little bit o patience. 
The pictured plant shows somewhat unusual dark flower color, and extra fragrant long-petaled blooms
 Nice show for the first flowering of that seed-grown plant.

Maihueniopsis darwinii hickenii

Maihueniopsis darwinii was described and pictured by J.S.Henslow  in 1937 after his friend C.Darwin, who discovered this plant in South Argentina during his sea travel. A single segment of the species was brought back in herbarium.
O.hickeny name first appears in Britton & Rose famous work, and is a larger form of that common in Argentina species, and has larger segments and longer spines, often curved. This is one of the easier to flower small Opuntiodes that deserves more popularity among collectors. Repotting it is always a challenge, as segments are too easy to detach. Over-potting them, to prolong use of same pot, seems like a good idea.

Echinocereis chisoensis

This uncommon Echinpcereus comes from small area in Big Bend National park, plains near Chisos mountains. As you can see, the geographical name is misspelled in the plant name - proper would be chisosensis, like Opintia name from same area.
This species has distinct easy recognizable look with shaggy spines and lots of fleck in areoles. Flowers are pretty large.

Oroya peruviana

Oroya peruviana has small but unusual flowers, and the plant I have produces them reliably every spring. Both shape and color make those little blooms to stand out.
Oroyas are nice and easy Peruvian plants, uncommon in collections.

Echinocereus coccinneus

Yet another E.coccinneus flower. The very spiny plant blooming for the first time, about 5 years from seed. Apart from long spines, this form has larger and lighter-red flower.

Echinocereus leonensis

Echinocereus pentalophus leonensis is a larger stemmed relative of more common E.pentalophus, and has very similar flowers, a bit more funnel-shaped. The larger plant I have is not creeping yet, with stems standing up about 20cm/ 8 inches. This is one of the stolon-forming Echinocerei. This species deserves been better known and more commonly presented in collections.

Mammillaria laui dasyacantha

This small clumping plant is 3 years old from seed, and flowering for two years already. This free flowering species is closely related to M. carmenae, another collector's favorite, but less common.

Echonopcereus reichenbachii 'albispinus'

This is one of the many E. reichenbachii forms, white-spinned plant with light pink flowers. Plants are small and flower young.