Plant trichomes (or hairs) are mostly observed on leaves and flowers, but rarely on seeds. The cotton fibre, a hair found on a cash crop that supports more than 100 million families worldwide, is an extremely long and fine specialised seed trichome; although it has been intensively studied, its evolutionary origin remains unclear. Tan et al., (on pp.1590-1599) identified clusters of trichomes at the base of petals that are regulated by the two key seed fibre regulators, GhMYB25-like and GhMYB25. Silencing of GhMYB25-like inhibited both seed and petal base trichome formation, while silencing of GhMYB25 only caused a mild fibre phenotype but significantly impacted petal base trichome growth, indicating that the regulatory network for petal base trichomes is simpler than that of fibre cells, despite sharing key transcriptional regulators. A morphological survey of different plant species revealed that when seed trichomes are produced, the petal base trichomes are always present but are more widespread than the seed trichomes. Collectively, these data indicate that petal base trichomes may have been the starting point for the evolution of seed trichomes by providing a simple regulatory pathway, which, when ectopically expressed in the seed epidermis, could have led to the production of rudimentary seed hairs. Recruitment of additional regulators would have been needed to form the more complex network responsible for the production of the valuable cotton fibres now used in textiles.