Description
of seeds belonging to the Angiospermae
(Leguminosae) The seeds of this species have a physical type of dormancy and so they require some form of treatment to break up the external integuments. One of the most common methods is to soak the seeds in boiling water for 12-14 hours. The heat source must be removed before the seed and mixture are added, 10 parts water to each part seed, this must then be mixed until it is cool. Once the water is removed, the seed should be dried in a ventilated atmosphere, but not exposed to direct sunlight, and then it should be sown as soon as possible. An alternative method which is simple and effective, is to use mechanical scarification to remove the seed shell. Sow in the spring.  Seeds of Acacia
Acacia dealbata Link (Leguminosae) Vegetative propagation very widespread, usually with approach grafting on A. floribunda or on A. retinoides.
Acacia saligna (Labill.) Wendl. fil. acacia (Leguminosae) See Acacia spp.
(Aceraceae) To maintain the high quality of the seed, the water content, which is usually greater than 30-40% at the time of natural dissemination, must not fall below 30-32% in A. platanoides, A. pseudoplatanus and A. saccharinum, whilst for other species, the level must be less than 15-30%. The seeds often have an endogenous type of dormancy in that the embryo requires a period of post-maturation which occurs during the cold season or during vernalization. The length of this period varies depending on the species, and within a species, depending on provenance. The seeds therefore need to be observed periodically, to assess their swelling, in order to interrupt the treatment before germination begins, and proceed immediately with sowing. sowing may be carried out with winged or wingless keys.
Acer campestre L. field maple, hedge maple (Aceraceae) Spring sowing with seeds stratified first in the warm for 3-4 weeks, and then in the cold for a further 12-24 weeks. Alternatively, seeds may be used after they have been vernalized for 13 weeks. See Acer spp.
(Aceraceae) Autumn sowing or in the springtime with seeds vernalized for 2-3 months. Before beginning stratification, it is advisable to scarify the pericarp mechanically or soak the seeds in cold water for 2 weeks. Vegetative propagation common. See Acer spp.
Acer opalus Miller (Aceraceae) Autumn sowing or spring sowing with seeds vernalized without a substrate for 4-12 weeks. From the third or fourth week of treatment, the seed blend should be checked frequently. See Acer spp.
Acer palmatum Thunb. Japanese maple (Aceraceae) Spring sowing with seeds cold stratified for 3-4 months. Whenever possible, sow immediately after the autumn seed harvest, mulching the beds. If using bought seeds, sow in the spring with seeds stratified in the warm for 4 weeks and in the cold for 4-12. Some authors mention an alternative method to interrupt dormancy, which consists in soaking the seed in water at 55°c for 24 hours. Vegetative propagation very common. See Acer spp.
Acer platanoides L. Norway maple (Aceraceae) The seed’s water content must never fall below 30%. How long stratification lasts depends on the provenance of the seed. We advise sowing immediately after the autumn seed harvest or keeping the seed (at -2 to -5°c) until February, when cold stratification should begin (4-6 weeks); the seeds can be vernalized even without the substrate. From the third week of treatment, it is a good idea to check the seeds to be sure that the low temperatures are not hindering germination. Some authors suggest up to 12 weeks of vernalization. See Acer spp.
Acer pseudoplatanus L. sycamore (Aceraceae) The winged seed (samare) can be kept for 1-3 years at temperatures varying between -6 and -1°c in air-tight containers. Moisture content must be 30% In this species, dormancy is caused by the presence of germination inhibiting substances in the seed coverings, because if the seeds are removed from these, then the embryo germinates normally. Autumn sowing or spring sowing with vernalized seeds. Cold stratification should last for 4-10 weeks, but it is a good idea to check the seeds after 20 days of treatment and interrupt in the case of premature germination.  Samare of Acer pseudoplatanus
Acer saccharinum L. silver maple (Aceraceae) Sow immediately after the seed harvest, in late spring as the seeds lose their vitality very rapidly. The germinability of the samare can nevertheless be maintained at acceptable levels for 18 months if straight after they are gathered, the temperature of the seeds is reduced to -3 to -1°c and their water content is no less than 45-50%. The seeds have no dormancy period and, sown straight after harvesting, they germinate rapidly, with seedlings coming up in the same year. Nevertheless, some may also grow the following spring. Vegetative propagation is very widespread. See Acer spp.
Aesculus hippocastanum L. common horse chestnut (Hippocastanaceae) The seeds of this species are generally recalcitrant and very prone to dehydration, so it is difficult to keep them, and their germinability declines rapidly. If the humidity content falls below 45-50%, germinability is seriously compromised. Autumn sowing immediately after the seed harvest, or spring sowing with seed which has been stratified cold for 3-4 months. If the seeds become partially dehydrated after harvesting, they should be soaked in tepid water. If, however, the loss in water content is high, rehydration will not restore the seed’s quality.
Aesculus carnea Hayne (Hippocastanaceae) A triploid hybrid between A. hippocastanum and A. pavia
Ailanthus altissima (Miller) Swingle (Simaroubaceae) Sow by the end of the winter or in the spring with seed which has been cold stratified for 3-8 weeks. Instead of vernalization, the seeds may be soaked in cold water for 24-48 hours. In A.excelsa it is possible to improve germinability by soaking the seeds for 72 hours in a 2.5% potassium nitrate solution.
(Leguminosae) Spring sowing with seeds which have been scarified either mechanically or chemically (soaking in concentrated sulphuric acid for 10-15 minutes and under running water for 15) scarified. Treatment with warm water (see Acacia sp) does not give such good results in this species as in other leguminous plants.
Alnus cordata Loisel. Italian alder (Betulaceae) For this seed to keep well at temperatures between -3°c and +3°c, the water content must be reduced to 5-7%. Sow by the end of February or in the spring if the seed used has been vernalized with or without a substrate for 4-6 weeks.
Alnus glutinosa (L.) Gaertner common alder (Betulaceae)
Amorpha fruticosa L. false indigo (Leguminosae) Autumn sowing or spring sowing with seed which has been vernalized during the winter. Mechanical or chemical scarification (soaking in sulphuric acid for 5-8 minutes) may be used as an alternative to cold stratification. Either cleaned seeds or one-seed pods may be used.
Araujia sericifera Brot. Cruel plant (Asclepiadaceae) Spring sowing, germination occurs rapidly.  Araujia sericifera
Arbutus unedo L. Killarney strawberry tree (Ericaceae) After the well-ripened fruits have been harvested, it is best to remove the pulp (by steeping or with other methods). Autumn sowing, or spring sowing in seed beds, with seeds which have been cold stratified for 30-90 days, followed by transplanting.
(Cornaceae) Vegetative propagation. |