Copiapoa vs. Eriosyce?

[BarryRice]

Embarrassing question follows...

In the cactus collections I'm helping curate at the University of California (Davis), amongst the Copiapoa, I've found a few unlabeled cacti. One flowered, and as I suspected, turned out to be an Eriosyce!

Is there a sure fire character to separate the two genera when not in flower?

I'll post a few photos of the offending beasts shortly, but they look a lot like C. echinoides....and E. curvispina!

[iann]

Almost by definition, the definitive differences are in the flowers, fruit, and seed. We generally don't assign a genus on the basis of counting spines or measuring how tall a cactus is any more. The genus Eriosyce is entirely constructed on the basis of the fruit, and Copiapoas fairly uniformly on the (mostly) naked yellow flowers.

A waxy bloom is a good sign you have a Copiapoa. Eriosyce really don't do that much if at all, but then not all Copiapoas do it either. Many Eriosyce have chinned tubercles, not usually a strong feature in Copiapoas. However, both genera have highly varied body forms and spination. Many of them are obvious, but there is a fair amount of overlap in the medium-size greenish plants.

[BarryRice]

Hey Ian

Thanks. I guess I'm just going to wait for these things to flower! Here are the six pots--the 7th pot on the right is an Eriosyce.

image.jpg (75.61 KiB) Viewed 983 times

Cheers

Barry

[iann]

Picture is a bit small and dark, but first guess is most of those are Copiapoas. Can't see the small one at the back at all. Front left might be Eriosyce.

What flowers did the tall one have? I would have thought it would be E. senilis but presumably not?

[BarryRice]

Hey Ian

The flowers were gone by for the most part, but I could see some pale pinks.

Sorry for the bad lighting. It's a dark stormy day, now the greenhouse lighting has come on, so everything is yellow!

[vlani]

Far left and right are eEiosyces, and front left as well. Anything with cotton top must be Copiapoa.

[DaveW]

Basic difference of course in flower is Eriosyce have hairy/bristly flower tubes whereas Copiapoa's are naked. Even in habitat Some Copiapos'a and Eriosyce can grow together and be confused out of flower. Eriosyce simulans gets it's name from the fact it looks like the local Copiapoa out of flower. To quote Graham Charles book:-

"It is called "simulans" because it looks so much like Copiapoa coquimbana that grows with it in it's natural habitat. In fact, they look so alike they are difficult to tell apart out of flower."

viewtopic.php?f=2&t=33589" onclick="window.open(this.href);return false;

If any flower remains on your plants are hairy or bristly, they are Eriosyce.