Rocklady facts for kids
Quick facts for kids Rocklady |
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| Holmgrenanthe petrophila | |
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Holmgrenanthe
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petrophila
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Holmgrenanthe petrophila, also known as the rocklady, is a special desert plant. It is a perennial plant, meaning it lives for more than two years. This plant belongs to the plantain family, called Plantaginaceae. It is the only species in its group, or genus, named Holmgrenanthe.
The rocklady grows as low mats of stems that branch out from a woody base. Its leaves have small spines along their edges. The flowers are yellow and shaped like tubes, with five parts that open at the end. Two of these parts point backward, and three point forward.
This plant is very rare. It is found in only about ten places. Most of these spots are in Titus Canyon and Fall Canyon. Both canyons are inside the California part of Death Valley National Park. The rocklady likes to grow in cracks in limestone walls, often on the north side of the canyons.
Contents
What the Rocklady Looks Like
The Holmgrenanthe petrophila is an herbaceous perennial plant. This means it has soft stems, not woody ones, and lives for many years. It has roots that spread out like fibers. The plant grows low to the ground, with thin, branched stems coming from a woody base. Because it often grows on vertical rock faces, its stems usually hang down.
Its leaves are round or shaped like a kidney. They have tiny spines or bristles along their edges and at the tip. The leaves are about 12 to 35 millimeters (about 0.5 to 1.4 inches) long. They are also about 14 to 27 millimeters (about 0.5 to 1.1 inches) wide.
In its natural home, the rocklady blooms and grows fruit in spring and early summer, from April to June. Its flowers grow one by one on very short stalks, only 1 to 4 millimeters long. The green sepals, which are like small leaves at the base of the flower, are narrow and pointed. They form an urn shape around the flower's bottom. They are about 9 to 13 millimeters long and have small spines, just like the leaves.
The flower has five petals that are joined at their bases. They form a tube about 20 to 24 millimeters long. The parts that open at the end of the flower are 7 to 12 millimeters long. Two of these parts curve backward, and three point forward. The flowers are usually sulfur yellow, or they can be white with a yellow center.
Inside the flower, the style and stamens (the parts for reproduction) stay hidden. There are four stamens of two different lengths. After the flower is fertilized, a round seed capsule forms. This capsule holds tan-colored seeds.
How Scientists Named It
The group (genus) Holmgrenanthe was created in 1985 by a scientist named Wayne J. Elisens. He created it just for the rocklady, H. petrophila. Before this, the plant was placed in a different genus called Maurandya.
Elisens thought the rocklady was very different from other plants in Maurandya. For example, the rocklady has short stems that form mats, while its relatives have long stems that climb. Also, the edges of its leaves and sepals are spiny, and its seed-producing part (the ovary) has only one chamber.
The name Holmgrenanthe honors Arthur H., Noel H., and Patricia K. Holmgren. These were "dedicated botanists," meaning they were very devoted to studying plants of the western United States.
This genus is part of a larger group called Antirrhineae. This group used to be in the Scrophulariaceae family, but now it's in the Plantaginaceae family.
Plant Family Tree
Scientists use something called "molecular phylogenetics" to understand how plants are related. This involves studying their DNA. While Holmgrenanthe hasn't been included in all these studies, other studies looking at how the plants look (morphological characters) suggest that Holmgrenanthe was one of the first plants to develop in its group. This means it might still have features from its very old ancestors.
Here's a simplified family tree of the Antirrhineae group:
| Tribe Antirrhineae |
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The Rock-Loving Species
The only species in the Holmgrenanthe genus is Holmgrenanthe petrophila. It was first described in 1935 by Frederick Vernon Coville and Conrad Vernon Morton. They called it Maurandya petrophila at the time.
The name petrophila comes from Greek words: "petro-" means "rock," and "-phila" means "loving." So, petrophila means "rock-loving." This makes sense because Coville and Morton found these plants growing on a north-facing limestone wall in Titus Canyon in Death Valley, California. As mentioned, the species was moved to the new Holmgrenanthe genus by Elisens in 1985.
Where the Rocklady Lives
After the rocklady was first found in Titus Canyon, more plants were discovered in the nearby Fall Canyon. It is known from only about ten locations, mostly in these two canyons. All these places are within the California part of Death Valley National Park.
The plant grows in cracks in limestone walls, often on the north side. These areas are usually covered by creosote bush scrub, a common desert plant. Scientists think Holmgrenanthe petrophila might be a "paleoendemic." This means it might have once lived in a much larger area. But as the climate became warmer and drier about 11,000 to 8,000 years ago, it became limited to the more sheltered and moist spots in desert canyons.
Protecting the Rocklady
As of July 2014, the California Native Plant Society lists Holmgrenanthe petrophila as "rare, threatened, or endangered in California and elsewhere." The state of California lists it as critically endangered. However, it is not listed as endangered by the United States federal government or by the IUCN Red List, which is a global list of threatened species. This means it's very important to protect its habitat in Death Valley.
See also
In Spanish: Holmgrenanthe para niños
