Spring awakening in the coldhouse

All of the photos in this post were taken at the beginning of April to illustrate some of the spring activity in my coldhouse. The plants have been kept dormant all through winter and received their first drink of water only a few days before these pictures were shot.


Flowering Lophophora williamsii (El Huizache, San Luis Potosí)

The first plant I want to show off is a flowering Lophophora williamsii grown from seed originating from the El Huizache, San Luis Potosí, Mexico population (the population Anderson assigned as the neotype for the species). These plants are from a more southerly location than the ones I'm usually growing and I'm happy to see they are coping so well with the cold conditions during winter. I was getting used to thinking of all L. williamsii varieties as self-fertile but according to the Cactus Conservation Institute, greenhouse breeding experiments by Bohata and colleagues in the Czech Republic and by Köhres in Germany have shown that plants from the El Huizache population are self-sterile and therefore obligate outcrossers (leading one to suspect a great deal of genetic diversity within plants from this population – in contrast to the self-fertile populations that have little to no genetic diversity among individuals as they outcross very little).


Lophophora williamsii (El Huizache) flower with long style

The flowers of the El Huizache plants also seem to have a very long style that raises the stigma well above the stamens, making it hard, if not impossible, for the plants to reproduce without the help of a pollinator.


Bumble bee having fun with a Lophophora williamsii flower

Speaking of pollinators a bumble bee visited while I took these pictures – unfortunately only this one Lophophora flowered at the time making it impossible for the bee to fertilize the plant. The bumble bees that are active in early spring are huge; I don't know much about bees but am told that these large slow individuals are queen bees looking for nectar and pollen to feed their newly hatched brood.


Lophophora williamsii (SB 854; Starr Co, Texas) with fresh fruit

One of the Lophophora williamsii (SB 854; Starr Co, Texas) plants that I recently repotted has spawned a fruit. This variety of Lophophora williamsii is self-fertile to an extent where it happily sets seed if you just shake the flower a bit.


Flowering Acharagma roseana (LX 578; Ramon Arizpe, Coahuila)

My Acharagma roseana plants (LX 578; Ramon Arizpe, Coahuila - “Ramon” should probably read “Ramos” but I'll stick to the information from the vendors seed list) are coming of age. The plants were started from seed 4 years ago and are all ready to flower, displaying a wealth of flower buds. Only one, shown in the picture above, flowered when I took the pictures. Unfortunately it will be a while before I can visit my summerhouse (and coldhouse) again – I hope at least a few of the flowers will be saved for then. My Echinocereus reichenbachii plants are also growing a multitude of buds, getting ready for a flower fest I would hate to miss.


Frost damaged Matucana madisoniorum

Until now I have focused entirely on the success stories but a few of my plants didn't like being without heat during winter. My Matucana madisoniorum definitely didn't like the cold conditions (even being wrapped in multiple layers of horticultural fleece). The plant is heavily marked by the experience but survives.

I also lost a few plants: a couple of Carnegia gigantea (saguaro cactus), a Cylindropuntia bigelovii (teddy-bear cholla), and a Cylindropuntia tunicata (thistle cholla); I managed to save cuttings of the chollas though. These plants were kept out on the terrace all summer and I probably left them out for too long, exposing them to the autumn storms so the plants were not able to dry out completely before winter. I'm especially sad about the Carnegia gigantea plants as they were great specimens and are now completely reduced to mush.

Coldhouse grown Lophophora williamsii - the next generation

Four years ago I started my first batch of coldhouse grown Lophophora williamsii (SB 854; Starr Co, Texas) from seed. I've lost a few plants to frost during the years but the survivors have coped surprisingly well, enduring the Danish winters in an unheated greenhouse without problems (that being said, I still worry a bit for the plants every winter ;-).


Flowering Lophophora williamsii (SB 854; Starr Co, Texas)

The plants are now old enough to flower and have been doing so freely all summer. The above photo was taken late June and today the plants are still flowering.

I have pollinated as many flowers as possible - if more plants flower at the same time the flowers are cross-pollinated, otherwise selfed. A cotton-tipped swab can be used for transferring the pollen from the anther and deposit it on the stigma.


Lophophora williamsii pollinated with the help of a Q-tip


Lophophora williamsii with pollen deposited on the stigma

The plants have already set the first fruits (the picture below was taken at the end of July) - I can't say if these fruits are the result of the flowers being pollinated 5 weeks before, but I'm currently conducting some experiments to get a better understanding of how much time passes between a flower is pollinated and the resulting fruit appears.


Fruiting Lophophora williamsii

As mentioned above I cross-pollinate my Lophophora williamsii plants when possible (I don't cross plants from different locations though). This might be a waste of time as preliminary studies by Martin Terry indicate that outcrossing is close to zero (i.e. selfing is virtually 100%) in natural populations and all individuals in a given population are clones. The study is based on data from three Texan populations, including Starr County, and the results are not definite - but if the results are correct it would also mean that my surviving (Starr County) plants are not more fit for the coldhouse, genetically speaking, than the ones that died off as they are/were all clones... and I thought I was witnessing a live "selection of the fittest" drama. Anyway, I'll harvest the seed soon to start the next generation of coldhouse grown Lophophora williamsii ;-)

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Read the comments for a discussion on the use of the word "clone".