From the 15th floor you can see all manner of Manhattan eccentricities on the street below. But how did the humdrum rooftop of a nearby apartment house suddenly become covered with a blanket of suburban grass? "No, not grass--you don't want grass," explains Stuart Gaffin, a research scientist tracked down at Columbia University who turns out to be the city's rooftop Johnny Appleseed.

A specialist in something called the Urban Heat Island, Mr. Gaffin has successfully campaigned to have over a half-dozen rooftops, including four at green-minded Columbia, entirely matted with small plants called succulents.

They sop up and vaporize rainwater before it can jam the city sewage treatment plants; they cut summer heat that can exceed 170 degrees on a roof. No mowing required. "They're nature's geniuses at staying cool," Mr. Gaffin says, while stepping across the resilient mat of sedum plants flourishing high over West 112th Street. He gestures to the city panorama and estimates 30 square miles of unused rooftop acreage that could be vegetating. "Twenty times Central Park!" he declares, sounding like a producer coveting Broadway.

Mr. Gaffin's gardens range from vegetation plain as the top of a pool table to more advanced mixes that resemble pointillist abstractions atop two roofs at the Bronx’s Fieldston Middle School. Students tend instruments measuring insulation, water conservation and other virtues of green roofs, which Mr. Gaffin says far outlast normal roofs. They have a weird urban serenity. Far from streetwise rats, the worst critters that have shown up are butterflies and crickets.

Bloat is one of the co-tenants of the place, a maisonette erected last century, not far from the Chelsea Embankment, by Corydon Throsp, an acquaintance of the Rosettis' who wore hair smocks and liked to cultivate pharmaceutical plants up on the roof (a tradition young Osbie Feel has lately revived), a few of them hardy enough to survive fogs and frosts, but most returning, as fragments of peculiar alkaloids, to rooftop earth, along with manure from a trio of prize Wessex Saddleback sows quartered there by Throsp's successor, and dead leaves off many decorative trees transplanted to the roof by later tenants, and the odd unstomachable meal thrown or vomited there by this or that sensitive epicurean--all got scrambled together, eventually, by the knives of the seasons, to an impasto, feet thick, of unbelievable black topsoil in which anything could grow, not the least being bananas. Pirate, driven to despair by the wartime banana shortage, decided to build a glass hothouse on the roof, and persuade a friend who flew the Rio-to-Ascension-to-Fort-Lamy run to pinch him a sapling banana tree or two, in exchange for a German camera, should Pirate happen across one on his next mission by parachute.

Pirate has become famous for his Banana Breakfasts. Messmates throng here from all over England, even some who are allergic or outright hostile to bananas, just to watch--for the politics of bacteria, the soil's stringing of rings and chains in nets only God can tell the meshes of, have seen the fruit thrive often to lengths of a foot and a half, yes amazing but true.

[...]

"Hhahh," Pirate, in a voiceless roar watching his breath slip way over the parapets, "hhaahhh!" Rooftops dance in the morning. His giant bananas cluster, radiant yellow, humid green. HIs companions below dream drooling of a Banana Breakfast. This well-scrubbed day ought to be no worse than any--

Will it? Far to the east, down in the pink sky, something has just sparked, very brightly. A new star, nothing less noticeable. He leans on the parapet to watch. The brilliant point has already become a short vertical white line. It must be somewhere out over the North Sea...at least that far...icefields below and a cold smear of sun...

What is it? Nothing like this ever happens. But Pirate knows it, after all. He has seen it in a film, just in the last fortnight... it's a vapor trail. Already a finger's width higher now. But not from an airplane. Airplanes are not launched vertically. This is the new, and still Most Secret, German rocket bomb.