巨型雜交風滾草在加利福尼亞蔓延

巨型雜交風滾草在加利福尼亞蔓延

California has enough to worry about on the invasive species front, thank you very much, but it's now also home to a monster hybrid tumbleweed.

加州在入侵物種方面有足夠的擔憂，非常感謝，但現在它也是一種巨型雜交風滾草的家園。

Researchers at the University of California, Riverside, have discovered that two large invasive species of tumbleweed have joined together to create a new invasive species of tumbleweed, and it's spreading quickly. They recently took a closer look at this large tumbleweed to see why it was thriving.

加州大學河濱分校(University of California, Riverside)的研究人員發現，兩種大型入侵物種的風滾草結合在一起，形成了一種新的入侵物種——風滾草。最近，他們仔細觀察了這棵巨大的風滾草，想知道它為什么會茁壯成長。

Now that's a tumbleweed. A truck bed-sized specimen collected by Shana R. Welles in Riverside, California. (Photo: University of California, Riverside)

They found that the species, Salsola ryanii, is much larger than either of its parent plants, which can grow up to 6 feet tall. Findings from their study published in AoB Plants show that the tumbleweed likely grows faster and stronger because it has two pairs of its of its parents' chromosomes.

他們發現Salsola ryanii這個物種比它的任何一種母體植物都要大得多，它們可以長到6英尺高。他們發表在《AoB Plants》上的研究結果表明，風滾草可能生長得更快、更強壯，因為它有兩對它父母的染色體。

Finding the tumbleweed

尋找風滾草

The monster tumbleweed was first documented by scientists with the California Department of Food and Agriculture back in 2002 in two areas of the state's Central Valley. The plant, a hybridization of Salsola australis and Salsola tragus, was found to have spread to a third area of the Central Valley in 2009.

2002年，加州食品和農業部的科學家在加州中央山谷的兩個地區首次記錄了這種巨大的風滾草。2009年，人們發現這種植物已經蔓延到中央山谷的第三個地區。

As UC Riverside explains, the "problematic" Salsola tragus, believed to have the most rapid spread of any introduced species, is found in 48 states. It first arrived on American shores in the late 19th century aboard contaminated shipments of flax seed from Russia.

正如加州大學河濱分校(UC Riverside)所解釋的那樣，在48個州發現了被認為是所有外來物種中傳播速度最快的“有問題的”紅腹角雉(Salsola tragus)。它第一次到達美國海岸是在19世紀末，當時是從俄羅斯運來的受到污染的亞麻籽。

'The potential to be a problematic invasive'

“潛在的有問題的侵入性”

But back to the unholy union of these two tumbleweeds. In 2012, researchers from UC Riverside found that Salsola ryanii had indeed spread well beyond the confines of the Central Valley to the San Francisco Bay Area and Ventura County, northwest of Los Angeles, in just over a decade.

回到這兩株風滾草的邪惡結合上來。2012年，加州大學河濱分校(UC Riverside)的研究人員發現，Salsola ryanii的確在短短十多年的時間里，已經遠遠超出了中央谷地的范圍，蔓延到了舊金山灣區(San Francisco Bay Area)和洛杉磯西北部的文圖拉縣(Ventura County)。

Welles notes that average folks won't be able to differentiate Salsola ryanii from the two species of tumbleweed that spawned it. The hybridized plant was identified via DNA testing of plant samples collected at 53 different sites. Of these sites, Salsola ryanii was present at 15 — or 28% — of them, contradicting earlier notions that it would not spread beyond isolated areas of the Central Valley.

威爾斯指出，一般人將無法區分Salsola ryanii和產生它的兩種風滾草。通過對53個不同位點的植物標本進行DNA檢測，鑒定出雜交植株。在這些遺址中，Salsola ryanii出現在其中的15個，即28%，這與之前認為它不會擴散到中央山谷的孤立地區的觀點相矛盾。

While Welles concludes her findings in a most ominous manner — "We are not aware of any plant neospecies whose range spontaneously experienced such a dramatic expansion. Salsola ryanii has every indication of being just as invasive as its highly invasive parents" — at least she and her colleagues have a sense of humor about it.

盡管威爾斯以一種極為不祥的方式總結了她的發現——“我們不知道有任何一種新物種的范圍能自發地經歷如此劇烈的擴張。豬毛菜ryanii種種跡象表明已是一樣入侵其高度侵襲性的父母”——至少她和她的同事有幽默感。