Trilliums have an interesting way of dispersing their seeds. The fruit is a round capsule on the end of a long stalk, which bends down to the ground as the seeds within are ripening. As the seeds mature, the pressure of their expansion splits the capsule open on one side, and the seeds fall to the ground in clusters. Each seed has a light-colored crest attached to it, which is equal to the size of the seed. This crest is called a strophiole, and ants love to eat it. The ants collect trillium seeds and bring them back to their nests, where they eat the strophioles and discard the seeds, thus dispersing them to different parts of the woods. Ants have been observed to carry trillium seeds as far as thirty feet from the plant.
Trilliums are very difficult to transplant from the wild, so resist the urge to do so and instead buy plants from a reputable nursery, one which propagates trilliums from seeds or by a process called rhizome wounding. This is the fastest and most reliable way to propagate trilliums, and involves cutting a shallow V-shaped groove in the upper length of a trillium rhizome (a thick root-like structure several inches below the soil). If the soil is gently removed from the top of the rhizome, this groove can be cut without disturbing the rest of the plant. Dust the groove with a fungicide, and cover with the removed soil. A full year later, uncover the rhizome again and you should see bulblets that have formed along the wound. Carefully remove the bulblets, replant and water thoroughly, and you should have blooming-size plants in one to two years.
It is also possible to propagate trilliums from seed, although it takes a lot of patience since the plants will not flower for four or five years. Collect seeds when the strophiole (the ant-attracting appendage) has turned from white to russet brown. Often the seeds ripen before the capsule splits, so occasionally pinch open a capsule and check the seeds for ripeness. The seeds should be sown immediately, or stored in damp peat moss and refrigerated until sowing. Sow the seeds in a shady outdoor seedbed enriched with lots of humus. Keep the seed bed evenly moist throughout the growing season. The seeds will not germinate this first season since they need to overwinter in order to break their dormancy. The following season they will produce a single rudimentary leaf, and should be left undisturbed. The third year they will produce a single ovate leaf, and when the plants go into dormancy in the summer, they can be carefully lifted and moved into containers or a nursery bed. By the fourth year they will produce their characteristic three leaves, and if everything goes well, they will produce another set of leaves and finally a flower in their fifth year.
http://counties.cce.cornell.edu/chemung/agriculture/publications/trillum.pdfSo if the nursery you purchased your trillium from is reputable, they could have gotten their plants from some place that does propagate them.
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