The Right Hand of Dextra, and, The Gods of Xuma by David J. Lake (DAW, 1977 and 1978)

TO THE PURPLE BORN

The key to life on Earth is the DNA helix, which determines all the characteristics of every living thing.  The helix, a series of molecules within the life cell, is a spiral—with a left-hand turn.

The planet called Dextra could have been a duplicate of Earth.  It teemed with life, both fauna and flora.  But on Dextra the helix of life had a right-hand thread.  And there could be no viable combination between the two life forms, the native and the invading Terran. 

So it became a battle on the part of the colonists to uproot the native Dextran ecology—purple plants and beasts with surprising intelligence—and replace it with Earth-born green.  But the planet fought back in its own way.  And the result is a science fiction novel that is unusual, exciting, and highly original. 

(I'm tempted to make a joke about Dextra's right hand, but all I'll say is that there's some very strategically placed vegetation on this cover.  Moving right along...) 

BARSOOM REVISITED?

If the universe is infinite, it follows that there may be somewhere real physical worlds that duplicate those of the imagination.  And when Tom Carson caught sight of the third planet of 83 Eridani he recognized at once its resemblance to that imaginary Mars called "Barsoom" of the ancient novelist Burroughs.

Of course there were differences, but even so this planet was ruddy, criss-crossed with canals, and its inhabitants were redskinned, fought with swords, and had many things superficially in common with the fantasy Mars of the John Carter adventures. 

But there were indeed vital variations that would eventually trip up the self-deceived science-fiction-reading travellers from 24th century Earth.  Therin hangs a tale that will delight and surprise everyone who enjoys the thrill of exploring a new world, especially one that seems peculiarly familiar.

(Why is our hero wearing ski boots on a desert planet?)

By the 1970s paperback covers had grown exceedingly dull—except for the genres of fantasy, science fiction and (oddly enough) gothic romance.  These DAW covers with their bright colours and exotic creatures are definitely eye-catching!