The butternut plant is monoecious as in pumpkins, and features distinct male and female flowers which require honeybees for effective fruiting. Butternut, in-fact, is the most common among winter-squash vegetables. butternut squash growing in the garden Immature butternut squash growing in the garden!. Its external surface has smooth, ribbed skin. Even so, the fruit varies widely in its shape and size; with individual fruit may weighing up to 15 kg. Interiorly, its flesh is golden-yellow to orange depending up on color pigments.