Echinopsis / Trichocereus

[coz]

The genus Echinopsis has been in use since its first description in 1837 by Joseph Zuccharini, but the word was proposed by Karl Linnaeus back in 1737. The word derives from the Latin "echinos" meaning hedgehog or sea erchin and "opsis" meaning appearance, a reference to these plants dense covering of spines. Initially it was used to classify relatively small cactus that fit this description and didn`t really include columnar cactus at all. Most columnar cactus at this point in time belonged to the genus Cereus, derived from the Latin word for wax light or candle.

In 1974 a botanist named Friedrich Gaimo concluded that Trichocereus and Echinopsis flowers were of the same type. His argument was that the ovary and floral tube lacked spines but possessed hairs, had a open or diffused type of nectary and two series of stamens. Due to Friedrich`s conclusions and on account of the fact that Echinopsis was the older genus, all species in the Trichocereus genus were reclassified into Echinopsis.

[Paul S]

This is absolutely spot on, thank you for posting it.

The only thing I would add is that it hasn't subsequently been universally accepted. Lots of folks - me included - use the names Trichocereus, Soehrensia, Lobivia etc. From the perspective of a gardener, rather than a botanist/taxonomist, I feel that some major distinctions have been lost by lumping all these genera into Echinopsis so I stubbornly cling to the 'old names'.

And that is all before we mention Leucostele

[mickthecactus]

I’m with Paul on this.

[RCDS66]

The only thing I would add is that it hasn't subsequently been universally accepted. Lots of folks - me included - use the names Trichocereus, Soehrensia, Lobivia etc. From the perspective of a gardener, rather than a botanist/taxonomist, I feel that some major distinctions have been lost by lumping all these genera into Echinopsis so I stubbornly cling to the 'old names'.

I absolutely agree

[coz]

This is absolutely spot on, thank you for posting it.

The only thing I would add is that it hasn't subsequently been universally accepted. Lots of folks - me included - use the names Trichocereus, Soehrensia, Lobivia etc. From the perspective of a gardener, rather than a botanist/taxonomist, I feel that some major distinctions have been lost by lumping all these genera into Echinopsis so I stubbornly cling to the 'old names'.

And that is all before we mention Leucostele

I am the same, as I have trouble pronouncing Echinopsis anyhow and its hard to teach an old dog new tricks

[Meangreen94z]

To me it doesn’t seem the South American genera have been studied and documented well. There are accepted species names that overlap with each other. Including different species names under multiple genera for the same specimen. To me I always view the columnar species as Trichocereus, the larger barrel species as Echinopsis, and the small species as Lobivia. I think that formosa and bruchii are different enough that I view them as Soehrensia.

[Paul S]

Those make the sensible divisions to my mind, too.

It seems Leucostele is the new genus for some of the tall columnars. That came out of nowwhere, but at least they are separating them off again.

[edds]

I thought the Echinopsis/ Lobivia distinction was also to do with flower size, colour and time - Echinopsis species generally larger, white and often night-flowering whereas Lobivia are smaller, coloured and diurnal flowering.

[edds]

And these factors are some of the problem with the classification has led to them all being lumped together - some Lobivia are more closely related to some Echinopsis and Trichocereus than the are to other Lobivia and vice versa. It seems pollinator choice has driven flower morphology and environmental factors have driven body size and shape more than relatedness.

(But in my own collection I still use Echinopsis, Lobivia, Trichocereus and Hildewintera to name but a few!)