It smells alot like grapefruit but tastes just like a lemon.

It doesn't look like my parents Ponderosa lemons. They are more in a circular shape like a small bowling ball. UC Riverside has some pictures at:
http://www.citrusvariety.ucr.edu/citrus/ponderosa.html


Phillip

Would this or could this be a hybrid

Looks more like a Sanbokan.
http://www.citrusvariety.ucr.edu/citrus/sanbokan.html

here's one already juiced

Ponderosa . link http://forums.gardenweb.com/forums/load/citrus/msg1021280322190.html?1

On my Ponderosa lemon there are currently two fruits: first is pear-shaped with smooth rind and the 2nd one is round with rough rind. So maybe there is one Ponderosa, but it just forms various fruits?

The whole plant:


Round and rough fruit:


Pear-shaped one:

Many different varieties of young citrus trees that are just starting to produce fruit for the first or second time produce fruit with a rough rind, and also fruit with a more or less neck. Later as the tree grows older the fruit become more of the standard round shape. Of course, there are varieties such at Minneola or ponderosa and others that always maintains a neck shape as part of their genetics. - Millet (789-)

link
the biggest lemon is my ponderosa lemons. Ours always have a "neck" on them: They are very if their round on our tree.

here is a photo of our tree (last year)

http://www.postimage.org/image.php?v=Ts1kPqy0
http://www.postimage.org/image.php?v=Ts1kPKv9


so I think it IS a Ponderosa Lemon

I'm amazed a tree can handle the size of that fruit Emily.

" it smells like a grapefruit, but tastes just like a lemon "
Sanbokans are sweet, like the perfect homemade lemonade.
Ponderosa tastes lemon like, with a tiny hint of other fragrance The seeds are fairly small for the fruit size.
Does the unknown fruit have seeds ??
Any chance it is a Pummelo ? Some varieties taste fairly sour outside the tropics. Their seeds are rather large.