The Martians are of course, within the book, literal, alien invaders, yet they also serve a symbolic function. “This novel firmly implanted in the popular imagination the image of Martians as monsters, and brought a new sensationalism into interplanetary fiction” (Clute and Nicholls, The Encyclopedia of Science Fiction, p. 777). As monsters, the Martians thus serve, in part, as “emblems of fear and symbols of guilt” (Clute and Nicholls, p. 818): fear of the unknown… fear of death…. fear, perhaps, that humanity is not the supreme power in the universe that it imagines itself to be; guilt, possibly, over the imperialist excesses of Great Britain (“…we must remember what ruthless and utter destruction our own species has wrought… Are we such apostles of mercy as to complain if the Martians warred in the same spirit?” p. 355; I.1). As Wells depicts the Martians (see, e.g., I.4; II.2), they are certainly monstrous, and thus evoke all the unpleasant associations human beings have of “the other,” that which is strange and different. In this case, however, any reaction of revulsion (such as those expressed by the narrator) carry ironic freight, for the text makes clear the fact that these Martian monsters may represent humanity’s future: “We men, with our bicycles and road-skates, our Lilienthal soaring-machines, our guns and sticks and so forth, are just in the beginning of the evolution that Martians have worked out” (p. 469; II.2). The Martians are, literally, living brains who utilize technology to work savage, selfish destruction—a metaphorical description of imperialistic humanity as Wells critiques it.
The red weed is an organic indicator of the Martian take-over of planet Earth. This specimen of the Martian “vegetable kingdom” is, in fact, specified by the narrator to be “a vivid blood-red” in color (p. 468; II.2)—perhaps symbolically mirroring the human blood that is being spilled, and on which the Martians feed (and, therefore, the blood of humans spilled by humans in the real world, that feeds rampant imperialism). The red weed, or red “creeper,” for a time “gained… footing in competition with terrestrial forms” (p. 468; II.2). It thus represents the extent to which the Martians nearly succeeded in making the Earth their own. It also, however, prefigures the Martians’ demise, for a “cankering disease… presently seized upon it” (p. 484; II.6). In its fecund yet transitory nature, therefore, the red weed is not unlike the biblical symbol of “the grass” and “the flower of the field”: “As for man, his days are as grass: as a flower of the field, so he flourisheth. For the wind passeth over it, and it is gone; and the place thereof shall know it no more” (Ps. 103:15-16, KJV). Life is fleeting, whether Martian or human—and it must not be stained with the bloodshed of imperialism.