In Herschel's Zoobotanica, dryads are described as being biologically human, with the exception of one crucial factor: they are born with flowers entangled on the insides of their nerves. "Between specimens," she writes, "cosmetic variations abound; yet we find in them several similarities that are cause for their common categorisation. The arboreal growth in the majority of harvested specimens begins at the base of the coccyx, spreading upwards in a bundle of cellulose-walled tissue that resemble the vines of ivies or morning glories. From thereof, they branch towards the extremities of the body, blossoming at nerve clusters and points of confluence, in inflorescences of no more than five at a time. The exceptions are those which bear the blossoms of the rose, for those are the most sacred of flowers, and only grow singly upon the branching nodules of the system; their bearers are often found wracked with pain, as the sharp thorns dig into their lungs with their every breath."
The brain of a dryad is a fragile yet beautiful thing: in Herschel's time, they were preserved by collectors for use as one-of-a-kind centerpieces in crafts and floral arrangements.
Herschel's diagrams show the roots of the plant system exiting through a kind of growth at the base of the small of the back of the specimen, ending in a branching length of fibrous, fleshy roots up to six feet in length. She describes at great length how the dryad must remain rooted in one spot throughout its long existence, lest it be unable to absorb moisture and nutrition and succumb to a withering death of both the body and the mind. Due to the location of the roots, dryads are often found in a kneeling position in the wild, which, when combined with their phototrophic tendencies, makes them resemble repentant sinners or devout worshippers. "It is not for the lack of a reason that the dryad was once called the 'saint-plant', or meshid hadrakha, of ancient Gladia," writes Herschel, not without some admiration.
The physiology of dryads lends their cognition unique properties unseen in other zoobotanica. "The fibers constrict and press upon the nerves of a dryad such that the flow of anima vitae is almost entirely impeded; as such, cognition and perception for the dryad takes place over the scale of months, following the natural rate of growth of its internal vegetation. Stunted rates of growth due to poor soil conditions and inclement weather can render the average dryad comatose for a period of years." This presented a challenge to the ancient Gladian cult of plant worship, who believed dryads, despite their seemingly vegetative state, held the power to grant wishes when suitably supplicated - that is, if they even heard them at all. Various methods of communication have been documented by historians, ranging from rituals involving the chanting of prolonged invocations in shifts for years, to the grounding of inscribed stone tablets for use as fertiliser. It is unknown (and, given the alien state of the dryad's mind possibly unknowable) if any of these methods are effective.
A far curiouser phenomenon is when the dryad finally blossoms, for that is the only time where it is allowed to dream…