Thanks to Barbara for the initial sighting. There appeared to be the one plant with multiple flowers, taking over this ANBG location. A similar flowering Red Passionflower was seen between this sighting and the adjacent Red Centre.
Red Passionflower "took off" over the last 12 months - widespread within ANBG, dense infestations outside the Gardens in the northern ANBG annex, the creek line between ANBG and CSIRO, the northern part of CSIRO, along Barry Drive on the strip between it and Nicholson Crescent and the lower part of Dryandra Street, and scattered locations within Black Mountain Nature Reserve. The known infestations outside ANBG have been removed, & ANBG staff are tackling it within the Gardens with the assistance of the Friends of Black Mountain. I've written an article about it that will appear in the coming issue of 'Fronds' (the newsletter of the Friends of ANBG).