Should have labelled the last one as Mamm guelzowiana.
This one's a bit confused; I bought it years ago as Malacocarpus sellowii, it then mutated into Wigginsia tephracantha, & now NCL says it should be Parodia erinacea. Running out of space for labels

and flowers out at present

I made a comment on Chris Rodgerson's recent posting (spiders' webs), but thought I'd introduce myself in a bit more detail. I've been growing C & S for over 40 years now. I've been a member of Sheffield branch for years. I'm limited to a 6 x 8 grenhouse, rather shaded now, so have resorted to v...