Recently, tasks asking for floral formulas and diagrams appear more often in olympiads.
Below you will find some notes on flowers.
Also I compiled a slide show
Here you will find digital flower website. Take a look!
Bellow there is an introduction to floral diagrams:
All you need to know about flowers and inflorescences:
Big thanks to Big thanks to http://faculty.etsu.edu/liuc/Lecture%2024.%20Flower-contd.pdf, http://www.cambridge.org/ and https://uqu.edu.sa/files2/tiny_mce/plugins/filemanager/files/4290002/Lecture%208.pdf.