Claude de Vert: "The clergy, however, and the monks retained the old fashion, cutting the hair short, and even shaving the back of the neck, as far as the ears. When to this fashion of wearing the hair was added the Tonsure at the Crown of the head, the hair left was in modum coronae, as ritualists speak" (qtd. in Pugin's Glossary of ecclesiastical ornament and costume, 233).
Carlo Andreini's manual of 1779 explains why the form of a crown was used: 1. as a reminder of Christ's crown of thorns and 2., a slightly more provocative simile: the crown signifies clerical perfection, because it is an unbroken circle. Notice, however, that most men after a certain amount of hair loss do not have the means for an unbroken circle.

Baroque hagiography counts Galgano Giudotti as a Cistercian – there is even an abbey named after him (see above) – but his connection to the order came after his death.  
Guidotti converted from a dissolute life at 32, became a hermit, and died at 33 around 1180, Cistercian monks founded an abbey at the site of his hermitage, but it soon became too cramped and the Abbazia di San Galgano was built in the valley a few hundred meters away.
The abbey of San Galgano was the first (and only) new foundation of the Cistercians in Tuscany, since they mostly took over existing Benedictine monasteries.
The following baroque rendering shows Galgano's conversion and referst to him, in the caption, as a Cistercian hermit.

Notice the conversion scene rendered beautifully in the background. The caption also claims that Cistercians cultivated his hermitage and made it into a claustral paradise. 
This is one of several hagiographical examples in the new English-language publication by Andrzej Koziel, Art and Mysticism in Silesia in the Baroque Period (originally published in Polish in 2006).