Among the oldest today known Spear Methods are Yang Family Spear(not Yang Taiji) and Yue Liu He Spear(Yues Six Harmony Spear).In Qi Jiguang book it says that every spear comes from Yang Spear. Both spear sets were created in Song Dynasty.
Anyway the Shaolin Meihua Qiang set is said to have parts of Yang Family(not Taiji) Pearl Blossums Spear, which makes it in parts an decendent of the Yang Family Methods.
The Yang Family spear consisted of two Spear sets. The Pearl Blossum Spear and the Flower Spear. For the Pearl Blossom Spear a very long spear was used(a Spear longer then seventheen feet) and for the Flower Spear a Spear less then seventheen feet.
Its seems not to be clear why this set is called Meihua Qiang. Shaolin has Meihua Quan, Meihua Titang Quan (I dont know if its a tradtional set) and Meihua DanDao( a version which was rearranged in recent times).
Its said that the creator of both fist sets was Jinnaluo Wang (紧那罗王).