Forthcome:
From Middle English forthcomen, from Old English forþcuman (“to come forth, proceed, arrive at, succeed, come to pass, come true, be born”), from Proto-Germanic *furþa- (“forth”), *kwemaną (“to come”), equivalent to forth- + come.
Loculus:
: a small chamber or cavity especially in a plant or animal body
so all I can decipher from the above is "be born from a plant/animal cavity". Maybe something to do with "springtime".
ie: spring lamb, new shoots, etc