de·cus·sate 
(dĭ-kŭsāt′, dĕkə-sāt′)
(dĭ-kŭsāt′, dĕkə-sāt′)tr. & intr.v. de·cus·sat·ed, de·cus·sat·ing, de·cus·sates
To cross or become crossed so as to form an X; intersect.
adj.
1. Intersected or crossed in the form of an X.
2. Botany Arranged on a stem in opposite pairs, at right angles to those above or below: decussate leaves.
[Latin decussāre, decussāt-, from decussis, the number ten, intersection of two lines (from the Romans' use of X for the numeral 10), a ten-as coin : decem, ten; see dek in the Appendix of Indo-European roots + assis, as (coin).]
de·cussate′ly adv.
decussate