1.13. Perennial Herbaceous Plants (Hemicryptophytes)
Many perennial herbaceous plants have a perennial root or roots, the rejuvenation buds of which occur near the soil surface. Daucus carota subsp. maximus, which is the wild progenitor of the cultivated carrot, develops in sites where the natural state of the soil was disturbed. When it is growing densely, it may serve as an indicator for disturbance. In the first year of its growth it develops a thick deep root, stores nutritional reserves, sheds leaves in summer, and enters drought dormancy. After the first rains, plants of the previous year sprout and develop a leaf rosette and an inflorescence (Fig. 2.1.54). Blooming takes place in spring (Fig. 2.1.55) and seeds are dispersed during the summer and the beginning of winter (Figs. 2.1.56, 2.1.57). After flowering and seed production, the two year-old plant dies. There are a few perennial herbaceous plants which live longer and these include: Cirsium phyllocephalum (Fig. 2.1.58), Atractylis comosa (Fig. 2.1.59), Gundelia tournefortii, Salvia judaica (Fig 2.1.60) and Peucedanum junceum.
Fig. 2.1.54: Daucus carota subsp. maxima is the progenitor of the cultivated carrot. The wild plant produces a leaf-rosette and a thick root in the first year. It blooms in the second year (as in this figure).
Fig. 2.1.55: Flowers with purple corolla develop at the center of the white umbel and construct an image of a large flower with a “bull’s eye” pattern, or a flower with a dark colored visitor. After anthesis the umbels close like a fist.
Fig. 2.1.56: A ripe umbel in summer (left). In its center are seeds with bristles, protected by empty umbellules. Shaking of the tall, stiff, dry plants by the wind, leads to gradual seed dispersal.
Fig. 2.1.57: Umbellules, partially empty, constitute the compound umbel of the wild carrot.
Fig. 2.1.58: Cirsium phyllocephalum is a herbaceous perennial plant with outstandingly beautiful flowers blooming at the end of summer.
Fig. 2.1.59: Atractylis comosa develops a leaf rosette at the beginning of winter, inflorescences (left) during winter and spring, and blooms in the summer. Its beauty influenced its common name in Arabic – shawk al-ghazal = the gazelle thorn.
Fig. 2.1.60: Salvia judaica develops a leaf rosette at the beginning of winter. It blooms in spring (left) and during the summer the seeds fall from the opened calyces (right).
Perennial grasses in which most of the above-ground parts dry out in summer, keep a lower part of their stems green. These include Andropogon distachyos, Stipa bromoides (Fig. 2.1.61) and Hordeum bulbosum (Fig. 2.1.62).
Fig. 2.1.61: Andropogon distachtyos growing among rocks. When flowering, each blooming stem carries a pair of spikes.
Fig. 2.1.62: Hordeum bulbosum is a perennial grass with round corms situated in the upper soil layers. Leaves develop in winter and inflorescences in spring. The long spikes (left) break slowly (right) and the diaspores penetrate into the soil.