Dear Dr Redfield,
Thank you for your reply.
A purchase order is for your benefit only, Elsevier do not require one, please see below link:
Elsevier accept 3 methods of payment, please see below link:
As previously advised your article can be made available via open access, however you must cover the cost of USD$3,000.
Please confirm if you wish to proceed, I will update our system and send the forms for invoicing.
Elsevier Support Person
Botany 2015 by the numbers and some plant identification
6 hours ago in The Phytophactor