Ideally, you need at least two.
On the web, theres LOADS of close ups of single flowers, but very very few of the whole plant. So, theres a niche for photos of the whole plant in my opinion.
A close up can be very misleading. A general view tells a far better story.
How many blooms (sparse, bountiful)? How tall? How broad? whats the foliage like? Are tiny flowers held on top of long stems? Is it basal clump forming, in which case it may be suitable for front of border,allowing a "see through" the flowering stems, so as not to hide plants behind. LOTS of things.
A view of the foliage is also useful in many cases.
A veiw of the plant in combination with other plants is VERY useful.
That makes at least four options.
By the way, we aim to provide at least two in our Catalogs on CD. Thats what drives me on in the hope we get success - interest from the suppliers! That is not easy, unfortunately.