Digitalis thapsi many characteristics of "D. purpurea" after four to five generations of cultivation, and that the former became indistinguishable from the latter, a report that was considered "probably" trustworthy by Charles Darwin. "D. thapsi" and "D. purpurea" hybrids are generally fertile. "Digitalis thapsi" is widespread in Spain. A biennial evergreen plant, it flowers in late spring. A study of the fruiting activity in "D. thapsi" showed that production, size and number of seeds were interrelated. Analysis has shown that seed weight is not related to the length of the cotyledon, and that the length of the fifth leaf can serve as
Plant-for-the-Planet President. In addition to the young people, one adult also serves on the board, in a position called the "Planet-for-the-Planet Secretariat". The goal of the Global Board is to give the organisation a focus and make organisation-wide decisions. Coordinated with the organisation, tree planting activities or "parties" are organised by students and children themselves. The students need to find foresters and environmental organisations to supply seedlings, and show them how, where, and when to plant. The funding needed to plant trees comes from individual and corporate donations. Plant-for-the-Planet promises to plant one tree for every Euro donated. The organisation also