I planted 3 Rouge pumpkins, 3 New England pie pumpkins, 3 "Sweet Mama
Buttercup" squash, an acorn squash, a butternut squash, and 3 yellow
hybrid zucchinis in a manure pile in my garden. The vines have gone
crazy and it's hard to tell what's what. I ended up harvesting a small
yellow squash/pumpkin and have no idea what it is! It is 5-6" across,
yellow (waxy looking) with small green lines, and has a cup-like end
where the blossom was. Is this just and immmature pumpkin? Previous
pumpkins I've grown were green then orange. Picked it four days ago and
it has maintained its yellow color? Could it be a cross? Does this small
fruit sound redognizable to anyone? Thanks. mag

In article , mag wrote:
I planted 3 Rouge pumpkins, 3 New England pie pumpkins, 3 "Sweet Mama
Buttercup" squash, an acorn squash, a butternut squash, and 3 yellow
hybrid zucchinis in a manure pile in my garden. The vines have gone
crazy and it's hard to tell what's what. I ended up harvesting a small
yellow squash/pumpkin and have no idea what it is! It is 5-6" across,
yellow (waxy looking) with small green lines, and has a cup-like end
where the blossom was. Is this just and immmature pumpkin? Previous
pumpkins I've grown were green then orange. Picked it four days ago and
it has maintained its yellow color? Could it be a cross? Does this small
fruit sound redognizable to anyone? Thanks. mag

Sounds like an immature orange buttercup type of fruit. The seed it
grew from was probably either a result of insufficient care to keep a
strain pure at a seed farm, or a packaging error at the seed company.
Or maybe some seeds from a squash you ate last year ended up in the
manure pile?

Any crosses that occur this year in the patch won't have an effect on
this year's fruit, but if you plant seeds of any of the squash you
grow, you'll likely have some unusual fruit next year. If you have the
space to do this, the results can be quite amusing!

Domesticated squash and pumpkins are mostly cultivars of three species
of Curcurbita. Your acorn squash and zucchini are C. pepo, the Rouge
Vif D'Etampes and buttercup are C.maxima, and the butternut is
C.moschata. Cultivars called 'pumpkins' occur in all three species.
The species don't hybridize, but cultivars within a species cross
readily.

You can distinguish members of the three species by a number of traits,
including leaf size, shape, markings and fuzziness, the appearance of
the stem of the fruit and how it attaches and the size and shape of the
seeds. The character of the flesh is generally different too. If you
study your plants, you'll figure out some of these traits.

Note that you can eat any of these squash immature as you do zucchini,
but some may have a more solid texture. When I get exasperated with
the squash vine borers, I grow a C. moschata cultivar called
Tromboncino Rampicante, sort of a very long narrow necked butternut,
and eat it immature as a summer squash. C. moschata cultivars are
resistant to squash vine borers because they have a harder, woodier
stem, unlike the spongier, softer-skinned stems of the other two
species.