Spike growth

Spike growth was a transmutation or alteration/enchantment spell that caused the vegetation in an area of ground to become needle sharp without changing its appearance.

Effects
This spell could work outdoors on any ground that could support plant life. Surfaces of bare stone, deep snow, desert sand, ice, or open water would cause spike growth to fail. When cast, the vegetation on the ground or roots and rootlets just under the surface became hard with sharp points, acting like caltrops to any who traversed the affected area on foot. Victims who tread on the spikes injured their feet and, unless they resisted the magic of the spell, were reduced in movement rate for the next 24 hours  or until cured for all the damage caused by the spikes. Having the wounds bound and treated by a competent caregiver for ten minutes could also allow the victim to move at full speed again.

The appearance of the ground was not altered in any way by this spell, making it very difficult to detect by normal means. A rogue had a chance to search and find this trap, but without true seeing or the like the extent of the hazardous area could not be determined. Magical detection methods such as find traps worked in the usual fashion. Spike growth was not a device and could not be disabled like one.

The transmutation version of this spell lasted longer on average, and affected an area twice as big as the alteration/enchantment version.

Components
The newer version of spike growth required only the caster's holy symbol or divine focus plus the usual verbal and somatic components. The older version also needed seven sharp thorns, either naturally grown or whittled from small twigs.