Bryophytes like moisture and shade but can withstand considerable desiccation. They can grow almost anywhere but in arid countries certain habitats are favoured, eg shady cliff ledges, rocks and walls, on soil and under boulders, banks of wadis, spring and water channels, and on trunks of trees and shrubs. In general in Arabia they become more abundant and conspicuous at higher altitudes.2. How to recognise bryophytes
Bryophytes comprise liverworts (Hepaticae) and mosses (Musci). All are small green plants reproducing by spores or asexual propagules (gemmae), with gametophyte (green part) and sporophyte (capsule) stages. Liverworts can either be flat (thallose), like Plagiochasma, or leafy like Plagiochila. Thallose liverworts often have margins which inroll under dry conditions to survive desiccation, and in Arabia they are much commoner that leafy liverworts which are found usually in shaded habitats at higher altitudes. Mosses are also often conspicuous in Arabia, and may be acrocarpous (erect-growing, with terminal capsules) eg Pleurochaete, or pleurocarpous (creeping, with lateral capsules) eg Hypnum.3. Collecting
A knife is an essential tool for collecting bryophytes. Those growing on rock or bark must be scraped off, those on soil should be collected with only a thin layer of substrate. Large moss cushions should be sliced vertically. Capsules are not essential but should be collected when present.4. Packeting
Bryophytes should be collected into paper packets or envelopes, and preferably not into polythene bags, unless they are to be transferred into packets within 24 hours. Packets are by far the best receptacle, as species can get very mixed up in polythene bags, and notes, field number etc can be written on packets on the spot. Only one species should be put in each packet., Folded A4 paper makes a practical-sized packet, but newspaper is quite adequate.5. Drying
Bryophytes require no pressing, but should be dried within 2-3 days of collection to avoid them going mouldy. Air drying is the best method, by spreading out the packets in a dry room or in the sun. In humid climates heat drying may be necessary. The packets should be stored in boxes, and should be bundled together with elastic bands before mailing.6. Data recording and labelling
Below is a typical label for the finished herbarium specimen, to show the type of information needed. These data are best recorded in the field in a notebook, along with a reference number which is also written on the specimen packet.
|David Long, Sept. 1982
Edinburgh Botanical Garden.
|Bryophyte Flora of Yemen Arab Republic|
Naqil Al Fardah, 60 km NE of Sana'a on Marib road. Among large boulders in limestone ravine.