Converts stearoyl-ACP to oleoyl-ACP by introduction of a cis double bond between carbons 9 and 10 of the acyl chain. Converts palmitoyl-ACP to (4Z)-hexadec-4-enoyl-ACP by introduction of a cis double bond between carbons 4 and 5 of the acyl chain. Catalyzes the desaturation of saturated fatty acid 18:0 and 16:0 to generate 18:1 (delta-9) and 16:1 (delta-4) intermediates, expected to give rise to 9-alkenes and 12-alkenes, respectively. 2 H(+) + hexadecanoyl-[ACP] + O2 + 2 reduced [2Fe-2S]-[ferredoxin] = (4Z)-hexadecenoyl-[ACP] + 2 H2O + 2 oxidized [2Fe-2S]-[ferredoxin] 2 H(+) + O2 + octadecanoyl-[ACP] + 2 reduced [2Fe-2S]-[ferredoxin] = (9Z)-octadecenoyl-[ACP] + 2 H2O + 2 oxidized [2Fe-2S]-[ferredoxin] Binds 2 Fe(2+) ions per subunit. Lipid metabolism; fatty acid metabolism. Homodimer. Preferentially expressed in the flower labellum. Flowers 9-alkenes and 12-alkenes function as attractants to the pollinator Andrena nigroaenea by mimicry of the bee's sex pheromones. Belongs to the fatty acid desaturase type 2 family. Unusual liaisons - Issue 145 of December 2012