How are ginkgo sperm cells unusual among seed plants?

Ginkgo sperm cells are unusual among seed plants because they are flagellated and motile.123

While most modern seed plants have evolved to rely on pollen tubes to deliver non-motile sperm directly to the egg, Ginkgo and cycads retain the primitive, ancestral trait of producing swimming sperm. These sperm are released into a fertilization chamber within the ovule, where they use their flagella to swim through liquid to reach the egg. This reliance on motile sperm is considered a transitional evolutionary condition, distinguishing Ginkgo from the vast majority of other seed-producing plants, which lack such structures.132