Question about Etrog Plants

[Joseph R. Metzger]

	I have some etrog plants which I am growing.  For those of you 
who do not know, an etrog is similar to a lemon.  They are usually grown 
in Israel.  Anyway, I am growing them and they have flowers, but the 
flowers never turn into fruit.  Do there plants need to be 
cross-polinated in order to have fruit?
	Any miscillaneous [sic] information about etrog plants would be 
appreaciated.  Please send me a letter at metzger at netaxs.com if you can 
help.  Thanks.