Nature #322 Rien Poortvliet (1932-1995)

The picture has something of this: cavalry, horse, seated, mare, equestrian, racehorse, bridle, stallion, mammal, equine, mane, chestnut, sorrel, saddle, pony, leather, dressage, two.
Perhaps it’s a drawing of a brown horse with a bridle on it’s head and a palm tree on the other side of the horse’s body.