Table 1.

Developmental stages sampled of balsam poplar trees at Indian Head, Saskatchewan, Canada.

Date sampled	Length of inflorescence bud (mm, bud scales removed)	Phenotypic developmental markers (female)	Phenotypic developmental markers (male)
21 June	2	Domed inflorescence meristem, no obvious floral primordia visible, No visible difference between male and female inflorescence buds
21 July	4	Floral primordia as raised bumps present over surface, No visible difference between male and female inflorescence buds
21 August	6	Slight difference from male in shape of the floral primordium (absence of stamen whorl)	Floral primordia well developed, some indication of floral organ development
21 Sept.	7	No stamen primordia visible, gynoecium primordium visible	Stamen primordia visible in most flowers
21 Oct.	8	Carpels well developed but small	Stamens well developed but small
21 March	10	Some enlargement of all floral organs	Some enlargement of all floral organs
2 May	15	Pre-anthesis female flowers fully developed	Pre-anthesis male flowers fully developed

Sampling occurred in 2017 (months 6–10) and 2018 (months 3 and 5).