1. (of a plant ovule) completely straight with the micropyle at the apex;
The Collaborative International Dictionary of English v.0.48:
Orthotropal \Or*thot"ro*pal\, Orthotropous \Or*thot"ro*pous\, a.
[Ortho- + Gr. ? to turn: cf. F. orthotrope.] (Bot.)
Having the axis of an ovule or seed straight from the hilum
and chalaza to the orifice or the micropyle; atropous.
Note: This word has also been used (but improperly) to
describe any embryo whose radicle points towards, or is
next to, the hilum.
WordNet (r) 3.0 (2006):
adj 1: (of a plant ovule) completely straight with the micropyle
at the apex [ant: campylotropous]