Foliar oil reservoir anatomy and distribution in Solidago canadensis (Asteraceae, tribe Astereae)

Publisher Website
Google Scholar
Abstract
In leaves of goldenrod, Solidago canadensis (Asteraceae, tribe Astereae), numerous internal oil reservoirs with a uniseriate epithelium occur as a single file above or below veins or as isolated cavities in the mesophyll. Reservoirs are abaxial to major veins (vein orders 1–3), either above, below, or superimposed in intermediate 4th order veins, but strictly adaxial to 5th and 6th order minor veins. Reservoirs are initiated as discrete cavities, but those below 1st and 2nd order veins are in a single crowded file, each separated only by epithelial cells. Elongation of these cavities, accompanied by stretching and separation of septa, gives a false impression at maturity of an indefinitely long duct instead of a series of tubular cavities. Reservoirs of vein orders 3–6 are mostly more widely separated and less subject to elongation, thus they are shorter and remain discrete at maturity. The overall foliar pattern is one of successively shorter reservoirs, a sequence that is in concert with the successively narrower and progressively less elongated vein orders. The shift from abaxial to adaxial reservoirs in minor veins may be related to different phloem functions: sugar transport in major veins and photosynthate assimilation in minor veins.