DNA yield from plant tissue.

[Michael Adamson]

Does anyone know the theoretical upper limit for genomic DNA/mg in
expanding eucalyptus leaf tissue?  I'm a bit worried that my 2ug/mg yield
from leaf discs is suspiciously high.  Even commercial kits advertise only
a 0.3-0.8ug/mg DNA yield.  The pellets are also a pink-purple colour, but
260/280 is always 1.8-1.9. Could RNA be the culprit (though there's only a
fairly faint smear at the bottom of my gels)?  I don't use RNase, but I
would have thought that not using RNA-grade reagents or equipment should
have resulted in much of it degrading - especially considering the 40min
incubation in non-sterilised lysis buffer. 

Any ideas greatly appreciated!