Tropaeolum notes

Jane McGary
Fri, 10 May 2013 12:59:24 PDT
Nhu wrote,
>I like growing Tropaeolum tuberosum and last year it dropped some seeds. A
>few weeks ago I was digging around preparing the bed for this year's
>planting and found some seedlings. It's a really interesting plant with
>nice flowers if you have the climate to grow it.
>Does anyone grow Tropaeolum speciosum? I love this species but I have not
>come across any seeds for sale/trade. When I was in Scotland, they were
>growing all over, even in someone's abandon front yard.

Tropaeolum seeds have a fleshy appendage that is attractive to ants, 
which carry the seeds some distance, even into their underground 
nests, eat the appendage, and leave the seeds in a good spot to 
germinate. Most of my T. brachyceras plants occurred as volunteer 
seedlings as a result of this ant dispersal (called myrmecophory). 
Another geophyte genus with this characteristic is Gymnospermium 
(formerly Berberidaceae, but I think it has been moved to another 
family). The seeds of both genera are quite large and fall out of the 
capsules very soon after forming.

Tropaeolum speciosum is not tuberous like most of the species we've 
been discussing. It has a widely spreading root system and comes from 
a wetter part of Chile, where it grows in moist woodland. I tried to 
establish it several times in my former garden, with no success, 
perhaps because the fast-draining soil there didn't suit it. It's 
best suited to cool-summer areas with plenty of rainfall. I may try 
it again now that I have a garden with more retentive soil. Although 
notoriously difficult to establish, once it settles in it is equally 
difficult to eradicate! A friend with a garden at the Oregon coast 
found the rhizomes with emerging stems even in the crawl space under 
his cottage.

Tropaeolum beuthii, mentioned by Clayton, comes from fairly low 
elevations in northern Chile and is quite similar to T. brachyceras. 
Presumably it is also winter-growing, so Clayton's question about how 
to "overwinter" it would have to be answered, "Give it adequate 
moisture and frost protection while it is in growth." It would have 
to be kept dry in summer. If Clayton lives in a very warm area with 
dry summers, he could grow it in a well-drained area in the open, but 
if it's frosty it would have to be kept under cover.

Incidentally, all these small Tropaeolum species flower much more 
heavily if given support to climb on. They can trail along the soil 
surface but will not bloom well there. In contrast, the larger 
species from up in the Andes typically sprawl on the soil surface and 
flower at the ends of the stems.

Jane McGary
Portland, Oregon, USA

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