It may be worth remembering that any specific description of the floral designs on the various Marseille decks remains either an interpretation made by the author, or an intended inclusion by the more recent artist (eg, the Camoin-Jodorowski, Hadar and Rodes-Sanchez decks).
Having scanned (and I must admit, only scanned or skimmed) numerous books in various shops in France recently, there appears to also be either paucity of material, or material that does little more than provide for personal insights (always, of course, very useful, but not to be taken as 'the' way of doing things).
In a reading situation, I would personally recommend more a sense for the card as it stands, paying attention to the manner in which the flower, bud, leaves, etc., appear to grow, decay, veer left or right, up or down, and the relationship this makes with other adjacent cards and the overall geometric pattern upon the card itself (of, especially, the implements depicted).
This does not mean that there is absolute randomness of signified meaning, but rather that the meaning in the moment will be partially determined by a combination of factors, such as background studies and insights on the implement (sword, cup, coin, baton), the geometric pattern of the implements and the number itself, and the relationship of the card to others in the spread.
Of course, many amongst us may also use an alternate system superimposed on the card, whether this be one such as that of the GD, or a Atouts/pip correlation, or an astrological one, etc. This only shows that a systemic way of approaching cards images which have a somewhat abstract depiction (as Marseille-style decks have) is often appealing. Appeal, however, does not indicate that the system provides deeper insights into the card as given, but rather as seen through the lense of the system itself.
In a thread some time back, I mentioned something about allowing the instrument to speak for itself, to teach its own tune. The more we seek to impose upon the depicted card image a system, the greater, it seems to me, the movement away from the card as it stands. This does not make, of course, the reading any the less accurate - a systemic way of doing a reading may be both quite accurate and assist in insights - but it does shape the manner in which the card is seen.