Rock Nettle aka Velcro Plant is one plant you for sure want to avoid when hiking.
Not only does it sting your skin, but it is also hard to remove from clothes.
When the leaves are green is when they will stick to your clothes and when the leaves are dry and brown is when they sting when you touch them.
DO NOT GO NEAR THEM!
What is Rock Nettle
Below is a transcription of the above sign found at the Valley of Fire Visitor Center.
Rock Nettle or Sting Bush – Eucnide urens
Community: Mixed Cliff Semi-Scrub
Habitat: Rocky canyons, common on cliffs and rock outcrops
Elevation: 1000 to 3000 ft (320 to 1000m)
Type of Soil: Limestone and sandstone
Source of Water: Surface, stored in rock crevices
Height: 1 to 2 ft (30 to 60 cm)
Pollination: Insects, wind
Adaptation for Survival: Leaves and stems covered with thousands of small, sharp-pointed poisonous hairs and shorter barbs which catch on animals passing by. Except for various insects and small reptiles, most animal life avoids this plant.
Comments: Contact with plant causes great discomfort. Skin soon develops a red stinging rash similar to that of the stinging nettle. Best to avoid this beautiful, interesting but dangerous cliff dweller.