A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, engages in photosynthesis, stores nutrients, and produces new living tissue. The stem can also be called the culm, halm, haulm, stalk, or thyrsus.
The stem is normally divided into nodes and internodes:
Bamboos are a diverse group of mostly evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in the case of Dendrocalamus sinicus having individual stalks (culms) reaching a length of 46 meters (151 ft), up to 36 centimeters (14 in) in thickness and a weight of up to 450 kilograms (1,000 lb). The internodes of bamboos can also be of great length. Kinabaluchloa wrayi has internodes up to 2.5 meters (8 ft) in length. and Arthrostylidium schomburgkii has internodes up to 5 meters (16 ft) in length, exceeded in length only by papyrus. By contrast, the stalks of the tiny bamboo Raddiella vanessiae of the savannas of French Guiana measure only 10–20 millimeters (0.4–0.8 in) in length by about 2 millimeters (0.08 in) in width. The origin of the word "bamboo" is uncertain, but it most likely comes from the Dutch or Portuguese language, which originally borrowed it from Malay.
In bamboo, as in other grasses, the internodal regions of the stem are usually hollow and the vascular bundles in the cross-section are scattered throughout the walls of the stalk instead of in a cylindrical cambium layer between the bark (phloem) and the wood (xylem) as in dicots and conifers. The dicotyledonous woody xylem is also absent. The absence of secondary growth wood causes the stems of monocots, including the palms and large bamboos, to be columnar rather than tapering.
Kinabaluchloa wrayi is a bamboo species endemic to the montane rainforests of Borneo. Its most remarkable feature is the length of its internodes which can be up to 200 cm (6.6 ft) in the lowest internode, gradually diminishing as the culm ascends to a mature height of up to 18 m (59 ft). The young culms are covered with black hairs.