"[O]ne of the fruits has unfurled its first leaves. You can see the tendrils starting to form, searching already for something to hang onto. You don't see any seed leaves (cotyledons), since they remain inside the chayote fruit, held together like the palms of two hands. We eat them when we eat the fruits. Being tropical, these fruits never form a hard shell for their seeds, and never go completely dormant. Well, I shall keep you posted. If this plant gets too long and rangy, I will have to trim it back before I plant it, but once it gets going, not much will stop it."Link.
Pam Peirce reports that three of her four chayote squashes have sprouted--and she has pictures.