Identify cactus

by Lynn
(Sandton, Gauteng, South Africa)

I am having trouble identifying the cactus I bought a week ago. I live in South Africa north of Johannesburg.

I think it is an Acanthocalycium spiniflorum

This is how I made the identification:

1. the site: www.cactiguide.com was the first place I found pictures and information that helped me:

- The plant bodies are globose up to 6 inches in diameter mine is about 6” in diameterand

- ribbed with between 16 and 20 ribs mine has 19 ribs that are partially separated into tubercles.

- Some may form small clumps, but they are usually single-stemmed plants - mine is single stemmed.

- Spines are about an inch or less mine is just over an inch and

- number between 10 and 20 per areole mine has about 12

-initially yellow-brown – mine are light yellow/golden but turning gray as they mature.
My plant looks like the the reference on their site for for another cactus in this genus – klimpelianum – except the spines are golden yellow.

I knew mine was not the A. klimpelianum because the site says it only grows to 4” in diameter and mine is already 6”.

The picture they have for Spiniflorum is not very clear but the description above matches my plant.

So, I was pretty sure until I found this on the www.cactus-art.biz site:

2. A. spiniflorus
Description: Solitary to slowly clumping.

- Stem: Globular to elongated, up to 60 cm tall, 15 cm in diameter. mine is 15cm in diameter
- Ribs: Numerous, 16 to 20, acute mine has 19 ribs

- Spines: 10 to 20 per areole, – mine has about 12; dense, thin, long, curved honey-coloured.don’t think this is correct – see CactiGuide pics on their site and description above that spines are about an inch long

In the cactus-art pic on their site, all but the spines looks like my cactus.In comparing the data on both sites, it is all about the spine length. If the spines are about an inch long, my plant is an A. spiniflorus. If they are long and curved, it is not.

Do you know which description is correct? Maybe, neither are correct and there is another description which is correct and I have not yet found it . . . Maybe, you have the answer for me.