12/19/2012 09:43 am ET Updated Feb 18, 2013

Mistletoe and Holly: Sinatra's Paen to Parasitism and Gender Issues?

"Oh, by gosh, by golly. It's time for mistletoe and holly."

So begins the only Christmas tune ever penned by Frank Sinatra. "Mistletoe and Holly" is a holiday masterpiece that elicits all the emotions that most classic Sinatra recordings do, including a yearning for the "good old days." One can listen to the seemingly simple message of this carol and be transported to a time when life, itself, was also simple.

But I know the biology of those two plants that Mr. Sinatra croons about... and that makes me wonder: Is there more to this song than standard Christmas cheer? Did Ol' Blue Eyes know more about those titular holiday icons than he let on? Could it be that beneath his infamously gruff exterior there lay the heart of a -- Dare I say it? -- botanist?

Mistletoe is best known today for its ability to get one kissed. You know the drill: If you can catch a guy or gal standing in the doorway beneath a ribbon-tied sprig, replete with ripened fruits, you can sneak in for a quick peck. Less romantic, to be sure, is the true nature of mistletoe.

While we tend to use only two species of mistletoe as holiday decoration, there are more than 300 species of mistletoe on Earth - and every one of them is a biological parasite. Mistletoes do not root in the ground; instead, they live among the branches of trees and shrubs where they use their specialized roots (called haustoria) to penetrate the stems, tap into their vascular systems, and steal energy on which they subsist. In this relationship the host plant gains nothing. The parasitic mistletoe garners all of the benefits.

Clearly, Sinatra knew what was going on here - as evidenced by the following lyrics:

Overeating, merry greetings
From relatives you don't know

I don't think I need to spell it out for you, but I will: A strange plant shows up at the door, seemingly friendly... a stranger, but also somehow familiar.... and then eats all of your food. It's biological poetry.

Hollies are not parasites, but they are unusual in their own right. Whereas most flowering plants might be considered hermaphrodites, with male (pollen-producing) and female (seed-producing) organs occurring in each flower, hollies are part of a small group of plant species that separate their sexes. Like we humans, hollies (and a few other things like willows and cannabis), mainly come in two genders. Female hollies are the ones we tend to use for holiday garland, their bright red fruits set against glossy evergreen foliage. Without a few male plants around to donate pollen, however, those fruits would never have appeared. The gender roles are clear in hollies, just like they are in Sinatra's lyrics:

Fancy ties an' granny's pies
An' folks stealin' a kiss or two

At Frank Sinatra's Christmas party, men wear the ties and women do the baking. Gender roles are defined and the sexes are separated -- except, of course, when romance is necessary to ensure that the human species may carry on. For plant species that produce both pollen and seeds on the same individual, finding a "mate" is not necessarily an issue. But for hollies, where male plants and female plants are separated, there will be no pretty fruits (and thus no baby hollies) unless somebody steals a pollen-loaded kiss (or two).

Sure, I could be reaching. It could also be a coincidence that Sinatra recorded songs like "Garden in the Rain," "Roses of Picardy," and "Flowers Mean Forgiveness." We could even choose to ignore the fact that the young Sinatra lived in Hoboken, New Jersey, in a house located on (gasp) Garden Street.

But it is also possible that this man had plants on the mind. And maybe -- just maybe -- "Strangers in the Night" is a veiled tribute to nocturnal pollination of desert flowers by giant, nectar-seeking moths.

A botanist can dream, at least.