Strawberry stems are divided into three types: new stems, rhizomes and stolons. The first two are underground stems, and the latter is a special overground stem of strawberry, which grows along the ground (Figure 3-3).

Figure 3-3 Strawberry Stem and Root

1 .new stem 2. Rhizomes 3. New root 4. Ancient roots

(1) The new stem The new stem is a short stem that germinated that year, and it is arched and planted on the rhizome. The new stem is an important organ for strawberry to develop leaves, take root, grow stems and form inflorescences. There are dense leaves and adventitious roots in the lower part of the new stem. The growth rate of new stems is slow, the annual growth is only 0.5 ~ 2 cm, and the growth of thick stems is relatively strong. Axillary buds are planted in the axils of the upper leaves of the new stem, which are precocious and can germinate to form stolons or branches of the new stem that year. A small number of new stem branches occur in flowering and fruiting period, and a large number occur in August-September, and the number of branches can reach 25-30 at most. However, there are great differences between different varieties, and within the same variety, it generally increases with age. The new stems and branches can be used as vegetative reproductive organs in ramet propagation to expand propagation. Axillary buds that do not germinate on new stems become hidden buds. When the shoots of strawberry plants are damaged, the hidden buds can germinate new stems or stolons and form new roots at the base of the new stems, so that the plants can grow rapidly. The terminal bud of the new stem can form a mixed flower bud in autumn, which becomes the first inflorescence of the arch back. Inflorescences all occur on one side of the arch back, and this characteristic is used to determine the planting direction of seedlings in production, so that inflorescences extend in the same direction.

(2) Rootstock The short perennial stems of strawberries are called rootstocks, which are transformed from new stems. In the second year, after all the leaves die and fall off, the new stems will become rhizomes. The rhizome structure is different from the new stem, and the rhizome has a high degree of lignification, while the vascular bundle structure in the inner layer of the new stem is developed and grows vigorously. Rootstock has nodes and annual rings, and is the main organ for storing nutrients. 2-year-old rhizomes often produce a large number of adventitious roots at the base of new stems. However, with the increase of age, the rhizome generally no longer has adventitious roots from the third year, gradually aging upwards, and dying from the old part below. Therefore, the older the rhizome, the worse the function of transporting, storing and absorbing nutrients, the more the aboveground growth declines, the smaller the fruit and the lower the yield. Therefore, two-year planting system or one-year planting system is implemented in production to ensure high yield and high quality of strawberries.

(3) Stolon Stolon is a unique overground stem of strawberry creeping on the ground, and it is the main organ of strawberry asexual reproduction. Stolons are formed by the germination and growth of lateral buds inserted in the axils of new stems and leaves. The newly grown stolons can grow upright. When it grows close to the height of leaf surface, its cambium and mechanical tissue are extremely underdeveloped and cannot be thickened, making the whole stem slender and soft, and it is difficult to grow upright and crawl on the ground. The internodes of stolon are very long, and there are lateral buds in the leaf sheath of each internode, but the lateral buds on odd nodes generally do not germinate and are in a dormant state, while the lateral buds on even nodes can germinate and grow normal stems and leaves and grow adventitious roots downwards. When adventitious roots are rooted in the soil, stolon seedlings can be formed. Under normal circumstances, stolon seedlings can survive independently in 2 ~ 3 weeks. With the growth of stolon seedlings, the primary stolon seedlings can differentiate into lateral buds in leaf axils, and the stolon will continue to sprout after the lateral buds germinate. These stolons still sprout from the lateral buds on even nodes, forming secondary stolon seedlings, and the secondary stolon seedlings can sprout three stolon seedlings (Figure 3-4).

Fig. 3-4 Occurrence of Strawberry Stolon