I am doing research into Greek and Roman mythology, specifically the underworld. There is supposedly a pomegranate orchard next to the palace of Hades, and I am looking for the ancient terms for it. https://www.theoi.com/Khthonios/HaidesTreasures.html I have found the term perivóli rodiás (περιβόλι ροδιάς), which I think is modern greek, and not ancient greek, for pomegranate orchard. Rhoa (ῥόα) is ancient greek for a singular pomegranate tree. In latin, malogranatum means pomegranate. Pomarium and hortis are latin words for orchards. Ascalaphus was the custodian of the orchard of Hades. https://en.wikipedia.org/wiki/Ascalaphus_(son_of_Acheron) So I have hit a wall with my research. Any help would be greatly appreciated.
Here's the Ovid passage in question:
cultis dum simplex errat in hortis,
Poeniceum curva decerpserat arbore pomum
While the carefree girl was wandering in the gardens,
She had plucked a pomegranate (poeniceum pomum) from a bent tree
So unfortunately, "pomegranate orchard" is not actually in the Latin. It's not an orchard at all. It's a hortus that has at least one pomegranate tree in it. However, I should note that the horti of the elite often had many different fruit trees in it, as is clear from Smith's Dictionary, citing Longus:
Longus (Past. II p36) describes a garden containing every production of each season, "in spring, roses, lilies, hyacinths, and violets; in summer, poppies, wild pears (ἀχράδες), and all fruit; in autumn, vines and figs, and pomegranates and myrtles."
I think the inclusion of a specific pomegranate orchard in the Underworld is due to the attribution of orchard-gardener to Ascalaphus, who told the gods that Persephone had eaten of the pomegranate, but the ancient evidence, as the above link shows, doesn't mention that particular status or a pomegranate orchard per se. Given the richness of the Underworld and the general fixation on eating its food (not just one particular fruit), the scene probably took place in a garden, though our best poem for it, the Homeric Hymn to Demeter, doesn't mention that either.
So I'd probably just call it a hortus, but if you want to make it clear that it's full of pomegranates, you could say:
hortus plenus pomorum poeniceorum
For Latin and as indicated by cmw's answer above, this comes from Ovid's Metamorphoses (in 5.536, link to Perseus) and only mentions the pomegranate as poeniceum pomum.
When it comes to Greek, it's actually from Apollodorus' Library (in 1.5.3, link) covering the same story that Ovid's myth is based on and expressed as ῥοιᾶς ἔδωκεν αὐτῇ φαγεῖν κόκκον (gave her to eat a pomegranate's seed), but there's no orchard mentioned in there either (if there was, it could possibly have been expressed as ῥοιᾰ́δων κῆπος).
If the English translation in question (either of Ovid or Apollodorus) had pomegranate orchard in its text, it would probably be because, depending on the translator, some tend to be looser than others to the point where words may be inserted that were not in the original.
The Latin word for "orchard" is the neuter noun, "pomarium" (Oxford). Literally, "a fruitery", a place where fruit can be found.
In his answer cmw has pointed out the Latin for "pomegranate" = "poeniceum-pomum"; literally, "a pomegranate-fruit". Therefore, what can a pomegranate-orchard be but a "poeniceum-pomarium" = "a pomegranate-fruitery" (orchard)?
Would the Romanns have said this? If asked about his pomegranates, a farmer might just have pointed to "illud pomarium" = "that orchard". If that is true, a pomegranate-orchard would have been called, "pomarium".
A Latin word for pomegranate is, as you rightly point out, malogranatum, although there is also malum punicum, which I will return to later.
So a Latin word for a grove of olivae (olive trees) is olivetum. We also have quercetum for a grove of quercus (oaks), and pinetum for a grove of, you guessed it, pines. In fact the suffix -etum seems very productive. We have nucetum for a nut orchard, vinetum for a vinyard, rosetum for a rose garden, spinetum for a thorn thicket, myrtetum for a myrtle grove, cypressetum for a cypress grove, and so on.
However, malogranatetum does sound like a mouthful, doesn't it?
I think I'd prefer malopunicetum, or even just punicetum. What do you think?