Why don't some succulents have thorns?
Almost all succulents without thorns come from South America and Asia. These are species in which the leaves have the task of performing chlorophyll photosynthesis, while plants with thorns (that is, those that have turned leaves into thorns over the centuries) entrust this task to the trunk. It is good to specify, however, the reason why many succulent plants are equipped with thorns, the result of a millennial process of natural selection. The thorns, in fact, constitute a way to protect themselves from living organisms that could attack plants, perhaps to use the water reserves that they have stored internally over time; moreover, they serve to keep the plant sheltered from very strong sun rays, which could cause irreparable burns especially in the newly hatched parts. From what has just been said, one can guess the reason why thorny plants without thorns need to be bathed more frequently, since they are not equipped with this barrier against the rays of the sun: without thorns, in essence, they must do accounts with a faster transpiration, and consequently with a faster process of water evaporation.
Some very common species
Among the species without more known thorns, we note the trichodiadema, which is part of the aizoaceae family. This plant, originating from South America but very widespread also in Europe, has stems capable of reaching a height of twenty centimeters, and owes its name to a kind of diadem located at the apex of each leaf, consisting of bristles of White color. Characterized by cylindrical and fleshy leaves, the trichodiadema proposes flowers that recall the daisy, and which, depending on the variety, take on different colors. It is a houseplant that is unlikely to withstand the cold of the winter months: some varieties are also used as ground cover, given the ease they demonstrate in occupying the entire space available to them. More succulent plants without thorns very well known are the lithops, also known as living stones. This species, originating from Africa, has a pair of leaves that are not very long, which resemble the appearance of stones and which are connected together at the bottom. The alpine lithops proposes gray leaves and yellow flowers, which are born in summer, while the beautiful lithops presents itself with leaves mottled with green. The flowers, in general, resemble yellow or white daisies - depending on the species - and last only a few days.
Succulents without thorns: rebutia, ideal plant for neophytes
Finally, in the review of succulent plants without thorns rebutia, belonging to the cactaceae, cannot be missed. It is a very suitable species for the less experienced, as it requires very little care and is particularly resistant. Coming from South America, in fact, it is able to survive even in situations of extreme dryness. We are dealing with a plant with a semi-spherical, globular shape, in which the thorns are replaced by decidedly soft filamentary bristles, which make it easy to handle and give it an almost woolly appearance. These whitish filaments completely cover the stem, and represent the aesthetic peculiarity of the rebutia. The flowers appear in the early days of summer, are voluminous and broad and are yellow, white or orange. Most of the plants bloom clearly more than once, due to their remarkable ability to proliferate: it is not a case that, starting from a single stem, it branches during growth both at the top and at the base. As far as cultivation is concerned, rebutia does not need an excessively rich soil of nutrients, and does not manifest special needs, in the sense that it is able to adapt to acid soils as to neutral soils. More attention, on the other hand, must be reserved for the temperature, which cannot fall below seven degrees. For this reason, if you intend to make it grow in the colder regions, in the winter months it is preferable to keep it sheltered in specific greenhouses, or alternatively shelter it at home avoiding any accentuated temperature range. Being a species accustomed to growing in arid lands, it does not need much water, and indeed if irrigation becomes excessive it risks causing serious damage. Water stagnation, in fact, in addition to risking freezing in the presence of low temperatures, can cause a weakening of the stem. A lover of southern exposure but not of direct sunlight during the hottest hours of the day, rebutia needs, over time, to be repotted when the growth of the root system makes it mandatory to switch to a pot bigger. Fertilization, on the other hand, must be carried out once every twenty days, in spring and summer, using a specific fertilizer for cacti. Robutia particularly suffers from cochineal, which can lead to the death of the plant infesting it: to avoid any kind of problem, it is necessary to eliminate the parasites using a small swab, or proceed with a definitive disinfestation using specific products.