Although lack of widely available databases of reproductive traits can be an issue, this manuscript overstates the need of standardization in floral biology for five reasons:
1. All techniques suggested are well known to any researcher in floral biology and are learned at early career stages or are easily learned in any field course. All of them are common sense, including the hierarchical sampling of floral units. The exceptions are the measurement of VOCs and flower colour, that require more sophisticated equipment (and a handbook is not going to circunvent this obstacle).
2. Description of how to measure these reproductive traits is widely available not only in the books by Dafni (1992), Kearns & Inouye (1992) and Dafni et al. (2005) (this one, not cited by the authors), but in any Material and Methods section of the immense number of articles about floral biology published every year.
3. Strong disagreement about how to measure these traits is overstated in the manuscript. The reason why the books mentioned in the point 2 "are difficult to find" (a statement that I very much doubt) is that there is no need to print a new version of these books because the methods are well established and no major advances have occurred (again, with the probable exception of measurement of VOCs and flower colour, where having the equipment is more difficult than agreeing on how to measure the traits). Browsing the recent and past primary literature on floral biology will show that no major discrepancies exist about how to measure reproductive traits (or that the impact of lack of standardization is seriously hindering advances in floral biology). An alternative to this handbook would be the reedition of the reference books.
4. Rather than standardization of methods, the problem is a lack of databases of reproductive traits. Nevertheless, the primary literature is full of basic data that can be mined, including quantitative floral morphology. nectar composition, pollen traits, floral phenology, floral longevity (over 900 species and 144 families in my personal database, and counting) and so on. In addition, databases of reproductive traits exist, such as PROTEUS, but may be not widely known. Of course, data are scattered across many papers and missing for each specific system of interest, but measuring, rather than standardizing, is the key missing step.
5. Lack of quantification is overstated in the ms. Floral morphology, floral longevity, floral nectar, floral phenology, pollen amount, ... are regularly estimated in quantitative terms in the primary literature on floral biology. Flower colour and VOCs have not been quantified until recently due to the cost of equipments but it is getting more and more frequent. Again, lack of standardization is not the problem; lack of the equipment is and no handbook is going to solve this limitation but funding.
It is possible to quibble about whether 24 traits are needed in general, or a much shorter list of reproductive traits can be enough for most studies. Researchers needing higher detail about nectar or pollen composition do not need a handbook, only more work. If the authors wish to put forward a higher awareness among the scientific community in the need to add traits to the list of reproductive traits regularly published in articles about floral biology, a shorter letter to one of the major journals seems a better way than proposing a handbook of reproductive traits.
Sincerely,

Marcos Méndez
October 2024

References
Dafni, A.; Kevan, P. G.; Husband, B. C. (eds.) (2005). Practical pollination biology. Enviroquest Ltd., Ontario.