difference between C. corsicus from C. imperati 'de Jagar'?

Jane McGary janemcgary@earthlink.net
Mon, 08 Mar 2010 09:53:02 PST
The wuestion was
>How does one tell the difference between C. corsicus from C. 
>imperati 'de Jagar'?  Does size matter?
>I have both growing next to each other in pots in a cold frame and C. corsicus
>sourced from a rare bulb seller in the Pacific Northwest began to 
>bloom first followed in 2 week by C. imperati 'de Jagar' from an 
>east coast reseller ultimately from a Dutch source. both are 
>blooming now and the only difference i can seen is C. corsicus  is larger.

Crocus corsicus has prominent dark feather markings on the outside of 
the outer tepals, on a lilac (sometimes nearly white) ground. C. 
imperati may or may not have the feather markings, depending on the 
form (I think 'De Jager' does not, or at least they are not heavy), 
but the ground color is yellowish or pale buff. This is the most 
obvious clue to identity.

The corm of C. corsicus is very strongly netted (reticulate) and that 
of C. imperati also reticulate but the fibers are longer and thinner. 
If you have a good lens, you can examine the underside of the leaves. 
In C. corsicus you will see longitudinal veins, one on each side of 
the keel, but in C. imperati these are absent.

It is very hard to tell C. corsicus from C. minimus (they both grow 
on Corsica), and some botanists think they should be a single 
species. The commercial selection of C. corsicus, which I think is 
the one you may have received from me, is large and strongly 
feathered. I also have C. corsicus grown from wild-collected seed and 
the flowers are quite a bit smaller. Some Dutch crocus selections are 
polyploid, meaning bigger and often more vigorous but likely sterile. 
I just heard this weekend (from John Grimshaw) that the Dutch 
selections of C. tommasinianus with the strong purple colors are 
either sterile polyploids or hybrids, and do not seed as the common 
"tommies" do, so if you want some and are very particular about not 
having anything spread, you could choose 'Whitwell Purple" or I think 
another one is called "Barr's Ruby". However, the C. tommasinianus 
selections 'Pictus' and 'Albus' self-sow freely. I have not seen seed 
on 'Roseus', though.

Jane McGary
Northwestern Oregon, USA

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