4. BULBS AND CORMS
This collection shows plants with a subterranean storage organ allowing the plants to survive under difficult conditions.
|Yndetulipan (Tulipa humilis)|
This collection shows plants with a subterranean storage organ allowing the plants to survive under difficult conditions. Those grown here have a resting period in two parts; first during summer drought, then winter cold. Many of them need to be cultivated in a south-facing, relatively warm slope on well-drained soil as an adaptation to summer drought. A large selection of species (e.g. 30 native tulip species) can be grown in Tromsø under such conditions. The stored nutrients allow the plants to flower early in spring – a good adaptation as their natural habitats dry out later in the season.
The storage organs are of different types. A bulb is the swollen lowermost part of the stem with modified leaves known as bulb scales. These store nutrients and do not form green leaf blades. Most of the species in this collection are of this category: onions and leeks (Allium), tulips (Tulipa), fritillaries (Fritillaria), grape hyacinths (Muscari) and lilies (Lilium). Crocuses and gladioli, on the other hand, have a corm without scales. Wood anemone (Anemone nemorosa) has swollen rhizomes as storage organs. Genera such as marsh orchids (Dactylorhiza), daylilies (Hemerocallis) and paeonies (Paeonia) store their nutrients in swollen roots.