Hecastocleis facts for kids

Quick facts for kids Prickleleaf
Hecastocleis shockleyi flowering heads
Scientific classification
Genus:	Hecastocleis
Species:	shockleyi

Hecastocleis is a type of plant with stiff, thorny branches. It belongs to the daisy family. At the end of each branch, you'll find groups of flowers. These groups are surrounded by oval, thorny, whitish or greenish leaves called bracts. Inside, there are several flower heads. Each flower head has only one pinkish bud that opens into a white flower.

There is only one species in the Hecastocleis group, and it's called Hecastocleis shockleyi. This plant is also known as prickleleaf. It is found only in the southwestern United States.

What Prickleleaf Looks Like

Hecastocleis shockleyi is a desert plant that grows in dry places. It is a thorny shrub, usually about 40–70 cm (1.3–2.3 ft) tall. Sometimes, it can grow as tall as 1.5 m (4 ft 11 in). This plant has sixteen chromosomes (2n=16).

Its Leaves

The leaves grow one after another along the branches. They are smooth or have a few soft hairs. The leaves are a bit olive green, stiff, and feel like leather. They have three main veins and are long and narrow, about 1–4 cm (0.4–1.6 in) long.

The base of each leaf wraps around the branch. The edges of the leaves are thick and usually have three to six spines. These spines are 1–3 mm (0.04–0.12 in) long. They are closer together near the base of the leaf. The tip of the leaf ends in a sharp point.

Its Flowers

The plant has many flowers grouped together at the end of its branches. These groups are called inflorescences. Each group is surrounded by white to yellowish-green, wavy leaves called bracts. These bracts have spiny edges.

Inside each group, there are one to five flower heads. Each flower head has only one small flower. The outer part of the flower head is called the involucre. It is shaped like a narrow vase and is about 1 cm (0.4 in) tall. It has about six layers of four small leaves called phyllaries. These phyllaries often have soft, woolly hairs around their edges.

The base of the flower head is flat. The flower itself is pinkish-purple when it's still a bud. When it opens, it turns pinkish-white and is about 1 cm (0.4 in) tall. These flowers have both male and female parts. They are star-shaped and have five narrow parts that point outwards.

The five pinkish-purple pollen parts (anthers) are joined together in a long tube. The female part (style) grows through this tube. It collects pollen on its hairs, showing it above the anther tube. This is common in daisy family plants. The style branches are very tiny, about 0.1–0.5 mm (0.004–0.020 in) long, with rounded tips.

At the bottom of the flower, a single seed develops. This seed is called a cypsela. It is not flat and has four to five faint lines. When it's ripe, it turns brown and loses any hairs. It is about 0.5 cm (0.2 in) tall. On top of the seed, there is a crown of six scales called the pappus. These scales are 1–2 mm (0.04–0.08 in) tall. They are shaped like spear tips and may have small teeth. Sometimes, they are joined at their base, forming a crown. The pollen of Hecastocleis is yellow and has three grooves.

How Prickleleaf is Different

Hecastocleis is special because its flower heads have only one flower. Some other daisy family plants also have single-flower heads. For example, Gundelia from the Middle East and Gymnarrhena from North Africa.

However, Gundelia and Gymnarrhena have separate male and female flowers. Hecastocleis flowers have both male and female parts. Also, Gymnarrhena male flowers have four parts, while Hecastocleis flowers have five parts.

How Scientists Classify Prickleleaf

Asa Gray first described Hecastocleis shockleyi in 1882. He placed it in a group called Mutisieae. Later, in 1994, Kåre Bremer put it in a smaller group within Mutisieae. In 2006, Hind created its own special group.

Modern Classification

Scientists now agree that Hecastocleis is very unique among the daisy family. Because it's so different, it has its own subfamily called Hecastocleidoideae. This means it's the only plant in that entire group.

Plant Family Tree

Scientists use genetic studies to understand how plants are related. The diagram below shows how Hecastocleis shockleyi fits into the daisy family tree:

Where Prickleleaf Came From

Scientists believe that the earliest daisy family plants came from southern South America. The plants that split off later than Hecastocleis mostly came from Africa, especially southern Africa, and some from Asia. This suggests that the ancestor of Hecastocleis and other later groups moved from South America to North America. After Hecastocleis branched off, the ancestors of the remaining subfamilies then moved from North America to Africa.

Another idea is that only the ancestor of Hecastocleis moved from South America to North America. Meanwhile, the ancestor of the other groups spread from South America to Africa. However, the genetic evidence strongly supports Hecastocleis being separate from the Gochnatieae group.

What Its Name Means

The name Hecastocleis comes from two Greek words. Hekastos means "each," and kleio means "to shut up." This refers to each flower having its own involucre, which encloses it. Another meaning for kleio is "glory."

The species name shockleyi honors William Hillman Shockley. He was an early plant collector in Nevada. He was also the father of William Shockley, who helped invent the transistor.

Where Prickleleaf Grows

Prickleleaf grows naturally in the desert plains and mountains of the southwestern United States. You can find it in eastern California, in Inyo, Mono, Kern, and San Bernardino Counties. It also grows in southern Nevada, in Mineral, Esmeralda, Nye, Lincoln, and Clark Counties.

It prefers dry, rocky slopes and flat areas. Some places where this plant has been found include Mount Charleston, the Nevada Test Site, Grapevine Mountains, and Red Pass.

Prickleleaf's Environment

In the mountains around the north side of Death Valley, Hecastocleis shockleyi can be one of the main shrubs. It often grows with plants like Atriplex confertifolia, Eriogonum fasciculatum, and Tetradymia axillaris. Other shrubs that are often present include Ephedra viridis, Ericameria laricifolia, and Lepidium fremontii. There are no trees in these areas.

Smaller plants like grasses form an open layer. These often include Achnatherum hymenoides, Bromus rubens, and Poa secunda. Other plants found here are Claytonia perfoliata, Cryptantha utahensis, Delphinium parishii, several Gilia species, and Phacelia vallis-mortae. You can also find soil crusts, lichen, and moss in this plant community.

Prickleleaf mostly grows on steep, very rocky slopes and rock outcrops that face north. It is found at heights between 1250 and 1600 m (4,100 and 5,250 ft). It usually grows in clay loam, loamy sand, or sandy clay soil. This soil comes from eroded dolomite, limestone, or shale, and it doesn't have many nutrients.

Scientists haven't yet seen how Hecastocleis is pollinated. But because its flowers are white, it's likely that insects that fly at night help pollinate it.

See also

In Spanish: Hecastocleis shockleyi para niños