Looking to trade for ramp seeds, licorice seeds or dragonfruit seeds.

I found the following link informative. Click on the physiological dormancy link on that webpage too. Here is a link that might be useful: Tulip poplar (Liriodendron tulipifera) Germination

Actually Tulip trees have perfect flowers, meaning they can self pollinate having both male and female parts in the same flower. For Tulip Trees, heavy seed crops tend to compensate for low seed viability (around 5-20 percent). The samaras are wind dispersed to distances 4 and 5 times the height of the parent tree. Seeds require a cold stratification period, and germination rates vary with time and temperature. Under controlled conditions, stratification in moist sand within a temperature range of 32° to 50° F for periods of 70 to 90 days resulted in satisfactory germination. However, seedling yield increases with increasing time of stratification. Generally as temperature decreases and time increases the germination rate increases; for example, 90 percent germination occurred after 140 days at 36 degrees Fahrenheit. Germination is epigeal and occurs when seeds remain constantly moist for several weeks. Seed Germination and seedling development is enhanced on mineral soil or on well-decomposed humus than on a thick, undecomposed litter layer. Germinating yellow-poplar seedlings need a suitable seedbed and adequate moisture to survive and become established. After germination, several critical years follow. During this period sufficient soil moisture must be available, good drainage and protection against drying and frost heaving are necessary, and there must be no severe competition from nearby sprout growth. In a study in which various mulches were used to induce soil temperature variation, seedlings grew faster in warm soil than in cool soil. Soil temperatures as high as 97° F had a beneficial effect on seedling growth.

Yellow variegated leaves in summer or yellow fall color? The typical plant produces nice yellow fall color, but there are also yellow variegated forms being grown. These last will not be as easy to find as non-selected seedlings. Here is a link that might be useful: Monrovia Plant Catalog Search - Liriodendron