Partial Sepal Peloria, or Partial Labelloidism, is when the Lower Half of the sepals (what looks to be the 2 lower "petals" of a cymbidium flower) attempt to mimic parts or almost all of the labellum (the bottom and largest 'petal' of the plant, also known as the "lip" of the flower).
While there have been several sepal peloric plants that may result out of a flask of seedlings, or mericloning of a specific cymbidium plant - MOST specific sepal peloric orchids in the past 30 years have been through the efforts of a few orchid nurserymen (and women) who have worked hard to hybridize for this one unique flowering characteristic.
The photos below are examples of Sepal / Ventral peloric cymbidiums I own, or have seen at orchid shows or at other friends' greenhouses.
