DESERT PLANTS

A cactus (plural: cacti, the word derives from Greek, thus the Latin plural "cacti" is etymologically inappropriate, though it is frequently used nonetheless as is otherwise singular "cactus") is any member of the succulent plant family Cactaceae, native to the Americas. They are often used as ornamental plants, but some are also crop plants.

Cacti are distinctive and unusual plants, which are adapted to extremely arid and hot environments, showing a wide range of anatomical and physiological features which conserve water. Their stems have expanded into green succulent structures containing the chlorophyll necessary for life and growth, while the leaves have become the spines for which cacti are so well known.

Cacti come in a wide range of shapes and sizes. The tallest is Pachycereus pringlei, with a maximum recorded height of 19.2 m,[1] and the smallest is Blossfeldia liliputiana, only about 1 cm diameter at maturity.[2] Cactus flowers are large, and like the spines and branches arise from areoles. Many cactus species are night blooming, as they are pollinated by nocturnal insects or small animals, principally moths and bats. Cactuses' sizes range from small and round to pole-like and tall.
The cacti are succulent plants that grow either as trees, shrubs or in the form of ground cover. Most species grow on the ground, but there is also a whole range of epiphytic species. In most species, except for the sub-family of the Pereskioideae (see image), the leaves are greatly or entirely reduced. The flowers, mostly radially symmetrical and hermaphrodite, bloom either by day or by night, depending on species. Their shape varies from tube-like through bell-like to wheel-shaped, and their size from 0.2 to 15-30 centimeters. Most of them have numerous sepals (from 5 to 50 or more), and change form from outside to inside, from bracts to petals. They have stamens in great numbers (from 50 to 1,500, rarely fewer). Nearly all species of cacti have a bitter sometimes milky sap contained within them. The berry-like fruits may contain few, but mostly many (3,000), seeds, which can be between 0.4 and 12 mm long.[3]

The life of a cactus is seldom longer than 300 years, and there are cacti which live only 25 years (although these flower as early as their second year). The Saguaro cactus (Carnegiea gigantea) grows to a height of up to 15 meters (the record is 17 meters 67cm), but in its first ten years it grows only 10 centimeters. The "mother-in-law's cushion" (Echinocactus grusonii) reaches a height of 2.5 meters and a diameter of 1 meter and - at least on the Canaries - is already capable of flowering after 6 years. The diameter of cactus flowers ranges from 5 to 30 cm; the colors are often conspicuous and spectacular.

TOUCH ME NOT PLANTS

Mimosa pudica (Sensitive Plant) (pudica = shy), is a creeping annual or perennial herb often grown for its curiosity value: the compound leaves fold inward and droop when touched, re-opening within minutes. The species is native to South America and Central America, but is now a pantropical weed
Description
The stem is erect in young plants, but becomes creeping or trailing with age. The stem is slender, branching, and sparsely to densely prickly, growing to a length of 1.5 m (5 ft). The leaves are bipinnately compound, with one or two pinnae pairs, and 10-26 leaflets per pinna. The petioles are also prickly. Pedunculate (stalked) pale pink or purple flower heads arise from the leaf axils. The globose to ovoid heads are 8-10 mm in diameter (excluding the stamens). On close examination, it is seen that the floret petals are red in their upper part and the filaments are pink to lavender. The fruit consists of clusters of 2-8 pods from 1-2 cm long each, these prickly on the margins. The pods break into 2-5 segments and contain pale brown seeds some 2.5 mm long. The flowers are pollinated by the wind and insects.[2]
Plant movement
Mimosa pudica is well known for its rapid plant movement. In the evening the leaflets will fold together and the whole leaf droops downward. It then re-opens at sunrise. This type of motion has been termed nyctinastic movement. The leaves also close up under various other stimuli, such as touching, warming, or shaking. The stimulus can also be transmitted to neighbouring leaves. These types of movements have been termed seismonastic movements. The movement is caused by "a rapid loss of pressure in strategically situated cells that cause the leaves to droop right before one’s eyes".[3] This characteristic is quite common within the Mimosaceae family.
Taxonomy and nomenclature
Mimosa pendula was first formally described by Carl Linnaeus in Species Plantarum in 1753.[4] The species epithet, pudica, is Latin for "bashful" or "shrinking", alluding to its shrinking reaction to contact.
Common names
The species is known by numerous common names including

sensitive plant[5]
humble plant[5]
shameplant[5]
sleeping grass[6]
touch-me-not[5].
The Chinese name for this plant translates to "shyness grass".[7] Its Sinhala name is Nidikumba, where 'nidi' means 'sleep'[8]. Its Tamil name is Thottal Sinungi, where 'Thottal' means 'touched' and 'Sinungi' means 'little cry'[9]. Other non-English common names include Makahiya (Philippines, with maka- meaning "quite" or "tendency to be", and -hiya meaning "shy", or "shyness")[citation needed], Mori Vivi[3] (West Indies), and mate-loi (false death)[citation needed] (Tonga).
Distribution
The species is native to South America and Central America. It has been introduced to many other regions and is regarded as an invasive species in Tanzania, South Asia and South East Asia and many Pacific Islands [6]. It is also regarded as invasive in parts of Australia. It is a declared weed in the Northern Territory[10], a declared plant in Western Australia, although not naturalised there[11], and control is recommended in Queensland.[12]

The species has also been introduced to Nigeria, Seychelles, Mauritius and East Asia but is not regarded as invasive in those places.[6]
Agricultural impacts
The species can be a troublesome weed in tropical crops, particularly when fields are hand cultivated. Dry thickets may become a fire hazard.[2] In some cases it has become a forage plant although the variety in Hawaii is reported to be toxic to livestock.[2][13]
Cultivation
In cultivation, this plant is most often grown as an indoor annual, but is also grown for groundcover. Propagation is generally by seed.
Uses
Mimosa pudica is sold as an educational product and novelty gift sometimes under the trademark name TickleMe Plant.[14]
Medicinal properties
The plant lajjalu described in Ayurveda has been identified as Mimosa pudica.[dubious – discuss] This plant has several alternate Sanskrit common names, including Namaskari, and Rakta Paadi.[citation needed]

In Ayurveda, the plant is described as a plant which folds itself when touched and spreads its leaves once again after a while. It is said to have a bitter and astringent taste, and has a history of use for the treatment of various ailments. Most commonly used is the root, but leaves, flowers, bark, and fruit can also be implemented.[citation needed]

A list of some of the notable chemical compounds found in Mimosa pudica can be found here: [1]
Ayurvedan Properties (guna) of Lajjalu
Has tikta and kashaya rasa (bitter and astringent taste).[citation needed]
Has property of cold (sheetha).[citation needed]
Balances kapha, pitta.[citation needed]
Shushrutha has placed this plant in Priyangwambhastaadi gana.[citation needed