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A single tallow tree can produce nearly 100,000 viable seeds annually that can remain in the soil for several years before sprouting. A mature stand can produce 4,500 kilograms of seeds per hectare per year. [17] These seeds are easily carried to different places by birds and water. Tallow trees can remain productive for 100 years. [17]
Trees portal; Tolerance of Tree Species; Silvics of North America, an encyclopedia of characteristics for around 200 tree species native to the United States published by the United States Forest Service. Zeigerwerte der Pflanzen Mitteleuropas (German) Archived 2015-08-07 at the Wayback Machine
The 6–12 mm (0.24–0.47 in) long, 4–7 mm (0.16–0.28 in) wide seeds are flattened ellipsoids and range from dark brown to black in color. The pods are mature and ready for propagation after turning from green to brown or black. Seeds are covered with a hard seed coat, and this allows them to remain dormant for up to 25 years.
Pokeweed is a member of the family Phytolaccaceae, and is a large herbaceous perennial plant, [9] growing up to 2.5 metres (8 feet) in height over the course of a summer. [9] One to several branches grow from the crown of a thick, white, fleshy taproot ; Michael D. K. Owen describes the branches as "stout, smooth, [and] green to somewhat purplish".
The seeds are winged and disperse by wind and water. Pollarded trees do not produce flowers, as these form only on mature wood. Paulownia tomentosa requires full sun for proper growth. [15] [16] It is tolerant of pollution and can tolerate many soil types [specify] [disputed – discuss]. It can also grow from small cracks in pavements and walls.
In northern climates they can be left outdoors during summer or placed under growing lights to promote fuller growth. When planted outside, the trees should be provided with adequate space, as they can grow to a large size. The trees are widely planted in coastal Southern California, where they can grow to well over 30 m (100 feet). [5]
Guanacaste seeds are brown and marked with a conspicuous light brown or orange ring. They are very hard, resembling small stones rather than tree seeds in their strength and durability. For germination to occur, the hard seed coat must be broken [5] to enable water to reach the embryo. Otherwise, the seeds lie dormant indefinitely.
A 300-year-old example growing in Grenzhammer, Ilmenau has allegedly been scientifically proven to be resistant to Dutch elm disease. [25] The Swedish Forest Tree Breeding Association at Källstorp produced triploid and tetraploid forms of the tree, but these proved no more resistant to Dutch elm disease than the normal diploid form. [26]