Previous plants of the week - the papaya
The papaya - Carica papaya L.
Blüten und Früchte der Carica papaya L.
Summertime is melon time - but do melons actually grow on trees? The melon tree family (Caricaceae) suggests that they do. However, they are not related to the real melons from the pumpkin family (Cucurbitaceae). The melon tree, better known as papaya (Carica papaya), only owes its name to the size, shape and color of its fruits, which resemble melons.
The tropical crop, whose fruit is mainly eaten raw, originally comes from Central America and is now cultivated in tropical and subtropical regions worldwide. The papaya fruit is round to pear-shaped, orange-yellow and contains numerous black seeds inside. It is considered to be very healthy and is rich in vitamin C, A and potassium. The pulp and seeds contain the protein-splitting enzyme papain, which is considered to aid digestion and is extracted and used in the food industry as a meat tenderizer and in the cosmetics industry, e.g. for skin care. Alongside other enzymes, it is also contained in the white latex of the plant. In traditional medicine, this is used to heal wounds, inflammations and burns.
Although the papaya plant bears an enormous fruit weight and can grow up to 10 meters in height, its shoot is not woody. Cross-linked bast fibers (phloem) in the shoot form the supporting structure. This fascinating stability also aroused the interest of biologists at TU Dresden (Kempe et al. 2013). Biomechanical studies showed that under experimental force, the tissue has a much lower bending stiffness than wood, for example. It is the interaction of the phloem fiber network, a high internal pressure in the plant's water conduction system (xylem) and the resulting tensile forces that are responsible for the stability of the shoot axis. Due to its special stem anatomy, the fast-growing papaya is able to quickly colonize gaps in rainforests and hardwood forests and thus shows a perfect adaptation to its habitat: it grows sufficiently stable with minimal fibre content. It demonstrates a central principle of life: the ability to remain sufficiently competitive with the least possible use of resources.
In the Botanical Garden, the papaya can be found at the back of Rainforest House II.
Kempe et al (2013): How to become a tree without wood - biomechanical analysis of the stem of Carica papaya L. Plant Biol 16 (1): 264-271https://doi.org/10.1111/plb.12035
(CW 28/25)
About 10,000 plant species grow in the Botanical Garden of TU Dresden. On this page we regularly present an example of this diversity in more detail. The special features of our scientific plant collection can be seen in many different ways: in amazing adaptations, strange names, interesting uses or even in the extraordinary splendor of their flowers.
You can view previous Plant of the Week articles in the archive.