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Morphology and Histology of anannas - Ananas cosmus Merr., Ananas..

anannas :

pine apple


Piña is a fruit bearing tropical plant with an erect stem, 0.5 to 1.5 meters high. Leaves are numerous, linear-lanceolate, 1 to 1.5 meters long, 5 to 7 centimeters wide, the margins sharply spiny-toothed, green and shiny on the upper surface, pale beneath. Leaves subtending the inflorescences are red, at least at the base and much reduced. Heads are terminal, solitary, ovoid, 6 to 8 millimeters long, much enlarged in fruit; with the bracteoles reddish, numerous, triangular-ovate to oblong-ovate, acute and imbricated. Sepals are ovate, thick and fleshy, about 1 centimeter long. Petals are three, oblanceolate, about 2 centimeters long, white below, violet-purple above. Mature fruit is up to 20 centimeters or longer.

Pineapple leaves - long, trough-shaped, tapered from base to tip, and approaching horizontal - are arranged spirally around the stump. This plant shape allows for maximum sunlight interception, and highly efficient gathering and movement of rain to the plant’s stem and root system. Most of the leaves – especially the leaves at the top of the plant most exposed to the sun are oriented at an angle to the sun (i.e. relatively erect) and this helps reduce leaf temperature and moisture loss. The leaves are arranged so that it is the thirteenth leaf on the spiral that first actually overlaps and shades a lower leaf on that plant, and because of their long, tapered shape do not shade leaves of neighbouring plants until they are large and mature. A mature plant, weighing 3.6 kg will have a leaf area of about 2.2 square metres.



The ovaries develop into berries, which coalesce into a large, compact, multiple fruit. The fruit of a pineapple is arranged in two interlocking helices, eight in one direction, 13 in the other, each being a Fibonacci number

Stomata Stomata are pores in the leaves that can open and close to the atmosphere. Carbon dioxide enters the plant through the stomata whilst moisture and oxygen leave through them. There are relatively few stomata per unit of leaf area, plus they are small and situated mainly on the underside of the leaves in depressed channels. Because they are small, deep and protected by a heavy coat of waxy trichomes, the plant has a very low rate of transpiration (water loss). 

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