Nice picture Doug. In the old days before present international conventions a specific name derived from a person used to be written with a capital letter and others with a lower case one, but now the "Code" say all generic names start with a capital letter, but specific names are to be written in lower case whether named after people or not, and the name italicised.
Hence Tillandsia Durati should be
Tillandsia durati if we are being pedantic. In fact the USA was one of the last countries that dropped the former practice of using a capital letter for specific names derived from people and came into line with the rest of the world. Zoological nomenclature is broadly similar.
http://www.anbg.gov.au/chah/avh/help/names/index.html
http://www.thewildflowersociety.com/wfs ... cation.htm
The underlining convention mentioned in the above link was mainly intended for typewritten script because most typewriters did not have the facility to write italics. Underlining a word I believe is the signal to printers to set in italics when composing for print.
DaveW