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I need help identifying one of my old neglected-so-far cacti. Unfortunately and somewhat deservedly, it has not flowered for me yet.

  • It is the size of an apple (since I have treated it horribly, or more precisely, not at all, it may well be undersized for its 10-year-old age)

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  • It has multiple (~20) prominent ribs. The ribs are straight (I'm thinking therefore this is not an Echinofossulocactus ( = Stenocactus)

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  • It has fibrous roots (I haven't got a picture of the roots, but I have repotted it recently and you will have to take my word for it)

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  • It has 4-6 spines per areola, one of which is noticeably longer than the others, reaching up to 3 cm in length. The spines aren't very strong, i.e. they'd rather bend than cut through the skin.

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  • The plant appears dusty, but if one takes a closer look, it seems the "dust" is some sort of wool on the stem. I don't know. Maybe not.

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I am thinking of Echinopsis (in the broad sense of the term, e.g. including Lobivias (Lobiviae?)) but because of the quantity of the species in the genus and the variability of plants I am having a hard time. Hope I'll get some good guesses here.

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Looks like Echinopsis rhodotricha, except the spines on yours are somewhat darker in colour in places, though this may be a trick of the light.

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  • Maybe you're right. Mine seems to have more ribs than the ones I see on the pictures that I could find on the web. On the other hand the stems on the pictures seem very different from each other. The only thing which unites them seems to be the flower. So flowers, if ever, will confirm. – Armen Tsirunyan Apr 6 '15 at 20:45
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    @ArmenTsirunyan - if you google it and select images, there are variations in numbers of spines, some being more and others less than yours. – Bamboo Apr 7 '15 at 9:09
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I'll guess that it's a Echinopsis hertrichiana (formerly Lobivia hertrichiana). It's hard to tell, though, because this is an extremely variable species, and some have fewer ribs, or more ribs, or deeper ribs, or more shallow ribs than your plant. Sometimes the ribs are more rounded, sometimes more pointy. Yours also looks unnaturally pale, but that might be the fault of the camera.

A lot of this variation depends on cultural conditions. The conditions that promote faster growth also promote the growth of fewer, more rounded ribs of a darker color, and greater distance between areolas. Plants with conditions that do not promote fast growth are not so intensely green, and are generally tougher and more spiny. And old plants have more ribs that young ones, even if the young one's bigger.

But the spines look very very close. It would help if it flowered, but it (obviously) hasn't. Here's a pic (of a far younger specimen) for some comparison:

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The cactus finally flowered. It is obviously Acanthocalycium spiniflorum (f. violaceum, if you will)

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