The don't require icons, but icons certainly fit a lot better. But that's true for anything, including toolbars and linear menus.

Various layout strategies have been developed for justifying text around the pie menu, some are better than others.

Rotating text is usually pretty terrible and hard to read because you have to turn your head and it's jaggy, but now days it's not quite as jaggy with anti-aliasing as PostScript graphics on a bitmap screen was.

The simplest thing to do is to define an inner label radius, and justify against it the center bottom of the top item (if there is one), the center top of the bottom item (if there is one), the left middle of all right items, the right middle of all the left items.

Here's a pie menu with iconic symbols justified that way, and a half pie menu with labels justified that way (just no bottom label since it has an even number of slices, and is half size):

https://cdn-images-1.medium.com/max/600/1*bK8djI5foFRHOjzCQc...

Here's an "eight days a week" menu that shows longer weekday name labels, including ones at the top and bottom -- it looks fine for wide text labels:

https://cdn-images-1.medium.com/max/450/0*4KdSEWpcoP4TM5Hy.g...

And here's a window management menu, that shows a menu with labels, and a grab submenu (for immediately grabbing a corner or edge) with icons.

https://cdn-images-1.medium.com/max/450/0*KkzlkTw5YG8zWJBu.g...

The top and bottom icons look a little hinkey since their center tops and bottoms are pinned against the inside label radius, so they're pushed out a bit too much. (It also may have to do with the icon metrics). To handle that, pie menus with automatic layout should let you tweak each item's exact position with a relative dx, dy offset (I guess I never got around to fixing that grab menu).

Here's a ringed menu with a shitload of very short single character labels, justified that way. Don't try this at home, kids! I'm not saying it's a good design, but I just had to try to see and feel how it worked. Somebody with better graphical design sense than I could do a lot better!

https://cdn-images-1.medium.com/max/300/0*e6Vki12PZpXhNUCF.p...

https://cdn-images-1.medium.com/max/300/0*Bp6mF8xuFoEXccz6.p...

https://cdn-images-1.medium.com/max/300/0*nS1dBKIaUJWAYGRK.p...

Another strategy is to use icons, but show a menu description when no item is selected, and the label of the selected item somewhere, like this:

SimCity Tools menu, nothing selected: "Select a SimCity editing tool, or the zone or build submenu."

https://cdn-images-1.medium.com/max/450/0*M4lyjaseU39Tvl9k.p...

SimCity Tools menu, bulldozer selected: "Bulldozer editing tool."

https://cdn-images-1.medium.com/max/450/0*ugqLx0GcRlCt7e_R.p...

Some of these images were from "OLPC Sugar Pie Menu Discussion" where there's lots more discussion about graphical design, layout, and tracking:

https://medium.com/@donhopkins/olpc-sugar-pie-menu-discussio...

The OLPC can get away with using a lot of nice big bold square icons, because it's designed for kids who may not be able to read. But I think it's important to support not just text labels, but also full text descriptions.

Another feature all kinds of menus should really have, is a way for users to discover why the fuck a menu item is disabled, and what they can do to enable it. It's so terribly frustrating that disabled items just ignore you and won't even let you select them, but there they are staring at you, not giving you any help, just watching you suffer, knowing all along what's wrong and why they're disabled, just not allowed to tell you!

At least let users point at menu items that aren't enabled, and tell them why they're not enabled in the help text at the bottom of the menu, and even provide some context sensitive hints describing what you have to do to enable the item, if not offering to do it for you.