She seemed very sweet and modest, having a pretty face and beautiful green eyes and hair. A dainty green silk skirt reached to her knees, showing silk stockings embroidered with pea-pods, and green satin slippers with bunches of lettuce for decorations instead of bows or buckles. Upon her silken waist clover leaves were embroidered, and she wore a jaunty little jacket trimmed with sparkling emeralds of a uniform size.
Since this was back when the green glasses I mentioned yesterday were still in use, Jellia's eyes and hair might not actually be green. In fact, she's usually drawn as a brunette, and she claims to originally be from the Gillikin Country. Later in the book, Mombi magically switches places with Jellia in order to trick Glinda. But it's actually generally agreed that her first appearance is in Wizard, as the unnamed "green girl" who waits on Dorothy. In fact, Ruth Plumly Thompson confirms this in Ozoplaning, which gives Jellia her biggest role in the series. For the most part, she's a perpetual background character, serving as Ozma's personal maid and the head of the palace staff. When she does appear in a major role in Ozoplaning, she still has some of her sprightly personality from Land, but she also seems more mature.
Jellia's role in non-canonical books is usually not that large, but a few of them do offer some interesting details. According to Mysterious Chronicles, her father's name is Jimb Jamb, and they're the closest neighbors that Mombi and Tip have. Jimb is also the only other person in the area to have a four-horned cow. And while this isn't strictly relevant, I created Jellia's cousin Jara as a character in my Sims 2 game, and the two daughters she had were Adora and Traffika. Dave Hardenbrook's recent book Jellia Jamb, Maid of Oz (which I reviewed here) gives Jellia a starring role, but also the habit of taking nude candy baths in the palace gardens, which seems rather far-fetched to me.