Cryptic flowers are often responsible for our sneezes. In Massachusetts, we have annual ragweed (Ambrosia artemisiifolia) to blame as one of the worst offenders. The small spikes of green flowers are so inconspicuous and drab, however, that it seems generations have attributed their runny noses in late summer and fall to more flamboyant suspects, like Canada goldenrod (Solidago canadensis), with its showy plumes of solar-hued flowers that illuminate roadsides.

Yet, sometimes, pollen allergies aren’t due to flowers at all, rather cones. In Japan, hay-fever season begins creeping north in late January, and the source for this early flush of runny noses is the Japanese cryptomeria (Cryptomeria japonica), otherwise known as sugi in Japan. Like all conifers, this large evergreen member of the cypress family (Cupressaceae) produces separate male and female cones. The male cones are small and abundant, massed between needles at the end of slender vegetative branches. The name cryptomeria refers to these small cones, translating as “hidden parts” from Greek. Even so, if you walk along Conifer Path at the Arboretum this week, you can easily spot the tiny cones from afar on two specimens (accessions 838-53*A and 545-53*A), given the amber highlight they cast on the otherwise dark, lustrous contours of the trees. Each small branchlet can carry as many as thirty-five cones, and yes, if you flick your finger against even one, an eruption of yellow pollen is guaranteed.

Charles Sprague Sargent, the first director of the Arboretum, encountered “great planted forests” of cryptomeria when he visited Japan in the early 1890s. The lumber was used for all manners of construction, he noted, and the bark was stripped for roofing material. (He also noticed that spherical bouquets of cryptomeria branches were hung over the doors of sake vendors. Although Sargent didn’t elaborate, this ornament, called sugidama, originated because the wood is rot resistant and ideal for sake barrels.) The large plantations Sargent observed expanded significantly after World War II, when the government doled out subsidies in an effort to amp production of domestic lumber. This, of course, only heightened the pollen problem. By 1995, The New York Times ran a headline declaring the cryptomeria forests were a “man-made disaster,” and pollen forecasts have now become a regular and highly monitored news story in Japan.

Nonetheless, Sargent noted the extreme beauty of cryptomeria, claiming that only the giant sequoia (Sequoiadendron giganteum) could rival the stately grandeur of the finest specimens. So, at the Arboretum, before darting between the magnolias and cherries that are restless to burst into flower, take a moment to track down one of the most infamous conifers of spring—but, please, noses beware!