figuring out inflorescences? need help
I am working an a computerized plant guide that translates
a key into laymens language. I have a biology background
but its in frogs not plants.
My confusion is this:
As I understand it there are inflorescences (non-simple ones) which are racemose (indeterminant so the older flowers usually appear at the base of the inflorescense) and those that are cymose (determinant so the older flowers appear at the top of the inflorescence). So far so good.
The confusion comes when I look at scorpoid and helicoid cymes. It would appear that the oldest flowers are at the base of the inflorescence yet these are classified as cymose. Of the examples I have looked at Phacelia stands out as appearing this way (its helicoid).
The only way it makes sense is if the first and oldest flower is considered the terminal one and all the others are coming off of one branch below it. It sure doesn't look this way though.
I looked at all the explanations on the web but there seems to be considerable confusion about the usage of the term
cyme (is it sometimes used casually to just describe the shape of the inflorescense??).
I apparently need to acquire a good botany text but I
haven't yet so please help me understand this if you can & recomend a good text if you know of one.