A few to ID if possible

[Andrew H]

A succulent is the first one - has red tips at the top if that helps.

[Andrew H]

Opuntia I think - could be wrong!!

[Andrew H]

Last one: a Mammillaria top and side view (2 pics).

[Andrew H]

This is the side view.

Thanks very much.

[Mike]

Andrew - I suspect thats's a form of Crassula arborescens. It looks a little like a form called Hobbit.
Mike

[Mike]

I only have two Opuntias (quite enough for me after being excrutiatingly entangled with one in California many years ago) - and your plant looks very much like one of them: mine's labelled as Opuntia cylindrica.
Mike

[Phil_SK]

Agree about it being the hobbit, but you'll find it in older books as C. argentea monstrosa or C. portulacea monstrosa. I don't think it's related to C. arborescens.

[Phil_SK]

I'd go for the monstrose form of Austrocylindropuntia subulata

[Andrew H]

Mike and Phil thanks for the ID's.

What to you mean by 'montrose' and 'hobbit'.

[Phil_SK]

Plants 'created' in cultivation, usually by crossing two plants together to make a hybrid are given non-Latin names, of which "Hobbit" is one. This website: http://www.lapshin.org/succulent/cras-l1.htm says Hobbit is a cross of C. portulacea and O. lactea.
Monstrose and cristate plants are both examples of plants 'gone wrong', for want of a better term. Fasciated is another word you might meet. Normal plants have a growing point which gets bigger equally in all directions to make a cylinder-shaped stem. In cristate plants this flattens to a fan shape. In monstrose plants lots of odd things seem to happen, particularly, growth from every bud. Picture a tree. At the base of each leaf is a bud. Most of these buds never form branches. Imagine a tree where every bud formed a branch. This is typically what monstrose cacti do.
If I find a good website I'll post it later, I'm struggling at the moment.