Herbarium specimen collected (RWP11454). Determination based on presence of numerous male flowers in inflorescence and leaves with midrib channelled on upper surface as shown in third photo where the leaf base wraps around the stem (see also http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&showsyn=&dist=&constat=&lvl=gn&name=Cortaderia).
How obvious are the channels in the midrib? My sighting Unidentified on 10 Mar 2019 shows pink inflorescence which from a distance could be either C. selloana or C. jubata. Once I hack my way through to the clump I would like to be sure how to distinguish the species.
I've added a third photo showing the upper surface of the leaf close to where it wraps around the stem where the channelling is really obvious; it's not as evident on the more distant parts of the leaf.
Thanks Rosemary. It's just the language: I would have said depressed rather than channelled. I went balloon watching today so visited this spot on Black Mountain Peninsula at the end of the balloon chasing. Now I know what to look for, though I would also like to see C. jubata (not the one I put on CNM).