Juglans nigra: Difference between revisions

The fruit production tends to occur irregularly with some years producing larger crops than others (see [[mast year]]). Fruiting may begin when the tree is 4–6 years old, but large crops take 20 years. Total lifespan of ''J. nigra'' is about 130 years. Black walnut does not leaf out until late spring when the soil has warmed and all frost danger is past. Like other trees of the order [[Fagales]], such as oaks, hickories, chestnuts, and birches, it is monoecious, with wind-pollinated catkins. Male and female flowers are in separate [[spike (botany)|spikes]], and the female flowers typically appear before the male on a single tree ([[dichogamy]]). As a consequence, [[self-pollination]] is unlikely. However, individual trees usually are notcommonly self-sterilecompatible; if they are not pollinated by neighboring trees, they may set self-fertilized seeds.<ref name="Silvics" /> For maximum seed germination, the seeds should be [[cold-moist stratified]] for 3–4 months, although the exact time depends on the seed source.<ref name="Silvics" /> The seedlings emerge in April or May. While most trees with taproots have a reputation for slow growth, black walnut is an exception and typicallycan growachieve very rapid growth in the seedling stage, typically {{convert|90|cm|in|round=5|abbr=on}} their first year and even more in the 2nd year.<ref name="Silvics" /> Black walnut oftenis losesone itsof leavesthe earlierlast thantrees otherin deciduousthe treeseastern growingUS to leaf out, usually in May, and one of the sameearliest areato afterdrop havingits aleaves, growingusually periodin ofOctober 115–135when the nuts are daysreleased.<ref name="Silvics" />

Black walnut is primarily a [[pioneer species]] similar to [[red maple|red]] and [[silver maple]] and [[black cherry]]. Because of this, black walnut is a common weed tree found along roadsides, fields, and forest edges in the eastern US. It will grow in closed forests, but is classified as shade intolerant, this means it requires full sun for optimal growth and nut production .