(1) In the figure, 1 filament, 2 anthers, 3 stigmas, 4 styles, 5 ovaries, 6 ovules, 1 and 2 are collectively called stamens, 3,4 and 5 are collectively called pistils, 2 anthers can produce pollen, and only 5 ovaries of a complete flower continue to develop after pollination and fertilization.

(2) Grafting refers to grafting buds or branches of one plant to another plant, so that the combined two parts grow into a complete plant. It can be seen that grafting belongs to asexual reproduction, and there is no process of combining sperm and eggs into fertilized eggs, so offspring generally do not mutate, which can maintain the stability of excellent characters of grafted scions, make fruit trees bear fruit early and enhance resistance, while rootstocks generally do not affect the heritability of scions. Therefore, excellent litchi. Screen tube is a conduit for transporting organic nutrients in phloem (inside bark) of plants. At the beginning of fruiting, fruit farmers usually cut off the bark of some branches in order to cut off the sieve tube in phloem, prevent nutrients from being transported downwards and increase yield.

So the answer is: (1) 2; 6; (2) grafting; sieve tube