Plum Blossom Fist, or Meihuaquan

Origins of this style are lost in legend. It is said that, when Zhang Sansheng teach in public, there are 100 generations of teachers before.

In many of the rural areas in which meihuazhuang has been practiced for centuries, the founding of the sect is attributed to the mythological figure Yun Pan. Villagers often say “Meihuazhuang existed since the beginning” and folk legends claim that its history extends to the Han dynasty. Meihuazhuang's oldest written records, genealogies and textual date to the records of 2nd generation master Zhang Sansheng.

— History of meihuazhuang

Other sources claim origin before Han Dynasty, but also in Shaolinquan:

Different versions on the origins of the Meihuaquan: a legend would make to come from the Shaolinquan in order to endure a successive change. An other quite maintain that the Meihuaquan would have been present before the times of Han Wudi Emperor(187-140 B.C.). Because lacking written reports it turns out impossibile make a textual search and informations depends from what my old Master, Liu Baojun, told:

the Meihuaquan would have origin from an ancient founder lived in not specify age, it synthetizes the ancient military tactics of our country and it is the quintessence of both Shaolin and Taiji. Meihuaquan is the result of experiences during years and years of study, of transformations and successive experimentations, becoming typical Chinese martial art. The author of the narration is a master of old generation . Meihuaquan is critical search of the movement models of Wushu and, in spite of the resemblance with Shaolin and Taiji, already it is changed (in a style to if being). Its meaning is deep and searched, for this reason becomes absolutely improper to compare it to the Shaolin or the Taiji. In the Meihuaquan there are many moving movements that they are instead absentees in the Shaolin and the Taiji. The oral story of my old Master has the value, therefore, of a written report.

— Chang Dsu Yao, Meihua Quanshu - Jianjie

 Meihuaquan and History

Stele of Yang BingSome Meihuaquan disciples believe that there are 100 generations of masters before the 20 after Ming Dynasty. During Qing Dynasty people who practiced this style were involved in various uprisings, like Wang Lun in 1774, Feng Keshan in 1813 and Zhao Sanduo in 1900 Boxer Uprising. (Meihuaquan was particularly linked with the early phases of the Boxer Uprising.) Another disciple, Yang Bing, was an Imperial Palace guard:

The history of this school (Meihuaquan) goes back at least to the kang-xi period, when it was taught by a certain Yang Bing, from Hua county in Henan, who had passed the highest military examination with third place honor, and served in the metropolitan garrison[30]
—The origins of the Boxer Uprising

Now we know that Yang Bing is a master of fifth generation and He born in Neihuangxian, not in Huaxian.

About Feng Keshan and Meihuaquan:

In the 1800s, Feng Keshan developed the Mei Hua Quan or Plum Flower Boxing style. This style was strongly based on internal chi circulation and large external circular movements. It was developed out of the Shaolin system. In 1814, Feng recruited members for the Eight Diagrams Sect (Ba Qua Jiao) and participated in an anti-Ching uprising. He was caught by the Ching Court, found guilty, and executed by dismemberment. The Mei Hua style was attributed to Wu Mei (also called Ng Mui), who was a legendary figure - a Shaolin nun, in order to disguise Feng Keshan`s underground activities. The style was essentially a condensing of Shaolin`s best techniques into one system and with its own footwork patterns (five directions) unifying the techniques.

—The history of traditional Chinese martial arts: Southern Style During the Qing Dynasty

 
Unfortunately there aren't other sources who confirm that the style was attributed to Wu Mei. Feng Keshan is a Eighth Generation. The legend of Wu Mei came from another style named Wumeihuaquan or Wumeipai and are founding also in some tale of Yongchunquan, a field completely distant to Feng Keshan history and Meihuaquan.