FWIW - not about spear forms but spear practice
The Wind Sweeps Away the Plum Blossoms
The Principles and Techniques of the Yang Style Tai Chi Spear and Staff
Translated and Compiled by Stuart Alve Olson
According to the translation Yang Luchan did not practice a spear form but rather 13 movements of the spear - similar to what is claimed regarding his dao practice.
"Within the Yang family tradition, the spear was abandoned for a time following the accidental death of Master Yang Panhou's daughter while sparring" [note: for a time abandoned but not forgotten or not practiced in later Yang family practitioners]
"However, it can be said that the Tai Chi spear techniques are the only true form of spear training whose principles and techniques are directed towards developing various internal energies" p.xvi {not quite true regarding its practice in other systems of Northern Chinese Martial Arts]
"A young friend of Chengfu a Mister Ho observed Chengfu demonstrate the practical use of the spear" p. 11
Tai Chi Thirteen Spear Methods
Tai Chi Spear Eight Postures
Actual photographs of Chen Weiming & Tung Ying-Chieh senior disciples demonstrating the 4 Part Spear pp. 15 -23 Also photographs of the sticky spear practice
Photographs of the actual practice of the Sticky Spear Techniques both solo and partner
Interestingly over all the years I have met both indoor and public students in the Yang Taijiquan lineage none has ever discussed if they continue the practice as part of their development.
In the Journal of Asian Martial Arts, Ben Lo, in an interview, stated that Zheng Manqing once offered to teach him the spear techniques but he politely refused - he said, paraphrasing, why should I learn the spear techniques when I have yet to master the open hand practice (personally I think the spear practice is part of the overall system development and not separated from the open hand practice)
I've never met any of the Zheng Manqing's students who practiced the spear techniques (not spear forms)
Pictures of TT Liang are also there doing the staff drills and practice. So TT Liang's might be the exception if you consider the part of the Zheng Manqing's lineage line.
I am wondering if anyone else has had a different/similiar experience with Yang practitioners both Yang Chengfu and/or Zheng Manqing students