Pterocactus araucanus

[Herts Mike]

Remove vegetative growth in winter? I haven't so far and it hasn't flowered. Always did it on tuberosus but the growths were much thinner and pretty much fell off on their own accord.

[DaveW]

I flower those type of Pterocacti without removing top growth. Mine usually go down below freezing in winter in an unheated greenhouse. I have even flowered P. tuberosus after leaving on three or four years top growth, but it often takes a year or two before they do flower again as the effort seems to go into producing the top growth rather than flowers.

P. tuberosus flowers regularly if you do remove the top growth, but being so flimsy presumably it looses the top growth in habitat more frequently than the more robust other species do? I am not a fan of planting roots above the soil either. I did once read that exposing tuberous roots of cacti slows down their development and the plants growth, plus possibly inhibits flowering. How true that is I don't know, but to me plants should always be planted at the soil level they are in habitat, since that is how they have evolved.

reticulatus2.jpg (104.18 KiB) Viewed 2681 times

I like Pterocacti, but they are rather untidy with top growth sometimes dying off at the tips and being terminal flowering the stem end has a cavity left after flowering so stops growing, needing to branch below, therefore not usually the pretty type of plant you will find on the show bench.

Note the cavity where last years flower was in the stem end of the one below and the new flowering stem coming out below it. The stem ends therefore often look as though they have been damaged, though this is perfectly natural:-

[RAYWOODBRIDGE]

Hi Mike; I would not touch the growth on P. aracanus but as you say P. tuberosus is almost self pruning,
your plant looks about the right size to start flowering.

Hi Dave; My P. fischeri (see picture below ) has now flowered on each of the three stems over the last three summers, so it will be interesting to see what happens next year, now that all the stems have a cavity in the top of them where the flowers where.

[nobby]

Hallo Mike,
if you want to see flowers it would be helpful to change some things in cuture. First of all your plant needs a really big pot. If the pot is too small for the tuberous root it will not be able to take up sufficient water and fertilizer. In nature (in the case of your plant this is near Zapala, prov. Neuquén) pterocacti are groing in sandy soil and the root is very deeply below the soil where it is always lightly humid and cool! In a small pot exposed to the sun in a greenhouse the root gets heated up and will be damaged. Sometimes it will nearly be cooked.
As your plant is not Pterocactus araucanus (this species will be described soon) it will produce flowering stems from below when getting a lot of water and fertilizer in early spring. In our region I start watering as soon as temperatures rise above 10°C even if temperatures may fall below zero during night.
The picture below shows how we pot our plants:

Best regards
nobby

[Herts Mike]

Thanks Nobby.

Why do you say it is not araucanus though?

I got this as a cutting from Kew Gardens in 2009 with the information that it had been collected by Dr R Kiesling and donated by David Hunt although the only information about collection was NW Argentina.

[nobby]

Hello Mike,

This plant is often mistaken for P. araucanus, but it differs by several characteristics:
e.g. flower, stem/segments, spination.
If you look at the article of Roberto Kiesling "The genus Pterocactus" in the Cactus and Succulent Journal of Great Britain Volume 44 (3): p.51-56 (1982) you can see, that P. araucanus always has an apical flower/fruit.
Your plant will very probably flower laterally with a purplebrownish colour. The flower colour of P. araucanus is always copper or orange to brass or darkyellow.
In the new book of John Pilbeam and Mchael Partridge "Small Opuntias" there is a good picture of P. araucanus on page 87 and a good picture of the wrong P. araucanus (your plant) on page 88. There you can see the lateral flowers.

Best regards
Nobby

[Herts Mike]

Unfortunately I don't have either of those publications to hand Nobby.

Bearing in mind this was collected by Roberto Kiesling you would think he would have known what it was but so be it.

Perhaps you would let us know the correct name once it is published?

[Phil_SK]

Mine grows very slowly, I don't think it'll be flowering very soon! I got it as a cutting about 10 years ago.

As your plant is not Pterocactus araucanus (this species will be described soon)

Congratulations on the 'birth' of your Pterocactus neuquensis!

[nobby]

Hey Phil,

I am surprised to see the name. As far as I know it will be published in September KuaS which has not arrived here yet. Who told you?

Best regards Nobby

I will tell more after publication is official (in two or three days).

[Phil_SK]

I'm not sure how it gets to me before it gets to you, but it's here!