Allium tuberosum
Sat, 08 Mar 2003 13:36:41 PST
Re: Allium tuberosum

Certainly an interesting range of responses on A. tuberosum.  I think Boyce 
Tankersley hit the nail on the head when he shared his experience gardening 
in two different climates; in one climate the species was well behaved 
whereas in the other it became an aggressive weed. Curiously, it is those 
respondants from mild climates that report the species as well behaved, one 
might assume it to happen the other way around!

I still grow this plant, but make it a point to deadhead, no matter how busy 
I might be.  That means cutting off inflorescences when there are still some 
open flowers... one of the drawbacks to this species is it's very quick 
ripening seed capsules which spoil the effect of the otherwise clean white 
flowers.  As I mentioned before, the flowers are apomictic, e.g. they're self 
fertile and make seed without cross fertilization. I've grown this species 
from numerous sources, but aside from the backs of the tepals handsomely 
nerved with red on some forms, there's little variation in the species.

Lauw de Jager wrote:  "Indeed at can spread by reseeding, but the rhizomes 
be easily removed (no bulbils are formed)".  
 - Actually, this species makes a deep-seated densely entwined mat of 
tenacious rhizomes, which effectively resists attempts at removal.  Many 
Alliums I grow, pop out fairly easily (bulb and all) when tugged on, but A. 
tuberosum is frustratingly difficult to pull out.  When it seeds in and 
invades other allium species, the best method of eradication is to spade the 
intermixed whole clump up, feather out the entrapped bulbs of the desired 
species and replant them.

Even though a thug (the Allium, not Lauw  :-)  I still like A. tuberosum for 
its sturdy stems in tight clumps and attractive white flowers late in the 
summer season.  When grown in sandy soil in sun, the plants remain fairly 
compact.  I think the oft-confused Allium ramosum is a better plant.

It is reported that A. tuberosum is frequently confused with A. ramosum, but 
I'm not sure why this should be.  Allium ramosum is a nice plant (reseeds 
modestly, never as weedy as tuberosum), flowering much earlier in June, with 
taller stems and ample white flowers, typically sporting a fine red central 
nerve down the back of each tepal.  The flowers are more open-funnel shaped 
compared to the wide open stars of tuberosum, and the inflorescence is more 
upright or fastigiate compared to the hemispherical domes of A. tuberosum.

I made a PBS wiki link to the person who previously uploaded A. tuberosum:…

Can the person who uploaded that photo let me know, and I'll give proper 
attribution to the wiki link.  

I have also posted a photo of Allium ramosum for comparison at:…

Both links have been placed in the newly created "Rhizomatous Onion" page at:…

Mark McDonough        Pepperell, Massachusetts, United States    "New England"               USDA Zone 5
>> web site under construction - <<
     alliums, bulbs, penstemons, hardy hibiscus, western 
            american alpines, iris, plants of all types!

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