This story has a lot of interesting innovations. Given its early timeframe, it's surprising that more of these innovations and this style didn't proliferate. Instead, sadly, it becomes an example of how the excitement and variety of the pioneering stage of a technology later collapse into the tried and true formulas of a mature technology -- the sad current state of affairs in SF, movies and computer games. Then again, this is why I'm inspired to spend my attention writing Technofiction rather than reading contemporary SF.
The first interesting aspect of this story is pansperma -- the idea that life originated on some other world and then came to earth in some form other than as an intelligent alien arriving in some kind of planet- or star-spanning craft. Pansperma is an enduring theme, and one that surprises me with its endurance. Why some people think it's so important that life did not originate on earth mystifies me.
But in this case, the theme is a nicely done example of technofiction. The heart of this story is aliens who are nicely original: they are intelligent plants. They don't move around, but they do think and plan. Plant chemistry rather than animation is their tool. And they are clever.
And the earth they come to is not contemporary earth. The plants and animals of earth have evolved too.
All-in-all, real good technofiction.
The author, Gallun, decided not to put the plants up against contemporary humans. His protagonist humans are living in the far future and are mean spirited descendants of humanity. I guess that's because in the end they lose, and he didn't want readers uncomfortable with that. (Also somewhat curiously, this story does not get mentioned in his Wikipedia article. According to that he was an SF pulp pioneer with a breakout story in 1934, and a modest award winner, but it appears he never became first-tier.)
The science in this story is nicely logical, but not particularly well tied to reality. The aliens come from Mars, and came to Mars eons before from gas giant moons. They move closer to the sun when their world gets old and cold, and they wait until the time is ripe. Not a bad concept. The waiting lets the author dodge the exponential growth issue. The sun, however, is steadily shrinking in brightness -- logical, but the opposite of what we now know, and there is no mention of an up and coming red giant phase. And the Moon's orbiting dynamics are also not described correctly.
Consistent, but not with reality. That's OK by me.
The invader is a spore that survives the cold, vacuum and dryness of a decades or centuries long, random walk journey from Mars to Earth. It and trillions of others are blasted off Mars by a specially developed super pods this plant species engineers and grows. OK... except that this tiny spore brings a whole lot of information along with it -- enough to grow an intelligent plant. That's might efficient information storage and retrieval.
This is pre-DNA times, so no one knew the chemistry of inheritance. But Gallun does describe a lot of chemistry as he describes his invader plants, and a lot of ecology. It's another impressive chunk of technofiction.
Interesting... there is feel for ecosystem, but little feel for a fitting together ecosystem. As spring breaks the world wakes up and is filled with more intelligent but more ferocious versions of animal life than we experience today... somehow. Somehow what we experience in the battles for survival are supposed to be walks in the part compared to this future dying world existence.
This alien creature is putting off spore pods in early spring, as well as developing anti-ant defenses. It's a busy, bustling little creature! But it's also neat. This is one of the memorable parts of this story.
The author makes the mistake of thinking that all animals are favored by more intelligence -- that there isn't an optimal amount for each lifestyle. It's a common mistake, one that I also experienced until a few years ago.
Gallun portrays the Itorloo, these Children of Men, as harsh and self-centered. The creatures of the Earth around them have gained in intelligence, but they have not. And they are dog-eat-dog defectors -- Neolithic Village thinking is enhanced. Interesting... Gallun has Zar, the Itorloo protagonist, even acknowledge as much, and then blames the lack of species advancement on wars and unrest killing off the kinder and gentler. But... no mention of Malthusian crisis with resources running out.
And, again as in all 30's-50's stuff, no good concept of what computers and communications will add to lifestyle.
define: Lethean (hypnotism) river of forgetfulness in Hades. (Greek)
Well... he can't quite do without an end-of-the-world cleche. In this it's the Itorloo acting like Morelocks and cutting bait on all surface life.
Oh my... a crow flying keeping up with a human flying machine and able to call out to the pilot. This is *really* early in flight days, I guess.
Interesting: Zar's ancient ancestors had visited Mars, and seen these plants' ancestors, and Zar has this knowledge. Gallun uses this as a plot device to fill us in more on alien history. Oddly, those ancestors didn't see much threat from the intelligent plants.
Not too surprising, we have Gallun coming up with an explanation for Lowell's canals of Mars. The plants ship water from the poles through plant tubes.