The pteridophytes (ferns, horsetails and lycopods) are an extremely ancient division of the plant kingdom, characterized by flowerless plants, which spread through spores and not seeds. They were the first to evolve on earth with well-vascularized tissues, distinct leaves, stems and roots. The Garden cultivates some examples: for example, among the ferns, Marsilea quadrifolia, which is very rare in Italy, or Dicksonia antarctica, with its majestic size; among the horsetails there are some Italian species, such as Equisetum hyemale, whose upright stems rise vertically reaching half a meter and creating a peculiar green architecture.
For a few years now the Garden has paid more attention to the species of native Lombard flora and has created a specific flower bed. Some plants, such as Allium suaveolens, Armeria arenaria, Agrostemma githago are now rare in nature because of land reclamation and the intensive farming of cereals. The flower bed was especially conceived to offer inspiration in the design of a flowered space in private gardens or on terraces, by using native species rather than species of exotic origin, which are often invasive and spread rapidly. The Garden also boasts an exceptional guest: the Milanese hawkweed (Hieracium australe subsp. Australale), Milan’s only endemic plant that grows exclusively on the walls of the Castello Sforzesco.
More than thirty hydrangeas thrive in the shade of the Garden’s large linden tree. While the collection is not extensive, it well represents the genus Hydrangea, including spontaneous species and various cultivars. They come from America as H. arborescens, H. quercifolia and from Asia as H. macrophylla, H. paniculata and H. heteromalla. Some of these mostly shrubby plant species remain small, less than one metre, but some of them can become very tall reaching several metres. Some species are climbers, like H. anomala subsp. petiolaris and the evergreen H. seemannii.
Peonies are unique plants botanically speaking: they all belong to the genus Paeonia, the only one in the Paeoniaceae family. Their stunning blossom is one of the enthralling spectacles of late spring. In the Garden there are both herbaceous species from Europe and Asia and shrubby species, hailing from several inland provinces of China. Among the former, P. officinalis stands out, which grows spontaneously in Italy or the Asian P. lactiflora, with its abundant flowers and strong scent, of which the Garden displays various cultivars. Among the shrubs, the most vigorous is P. ostii with the ‘White Phoenix’ and ‘Pink Phoenix’ varieties, with white flowers and the distinctive purple reproductive organs. P. lutea stands apart from all the other plants, being the only one with yellow flowers.
Plants belonging to the genus Salvia form one of the largest and diverse collections in the Garden including about forty species of various origins, with considerable morphological variability. Together with the Italian native species, such as S. glutinosa or S. verticillata, there are sages of tropical origin, which manage to adapt to the climate in Milan. They can grow to more than three meters and boast garish blooms, such as the deep blue of S. guaranitica or the bright red of S. elegans.