Therophyte


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therophyte

[′ther·ə‚fīt]
(ecology)
An annual plant whose seed is the only overwintering structure.

Therophyte

 

an annual plant that survives unfavorable seasons—cold or dry seasons—in seed form. Most therophytes are of Mediterranean origin and are characteristic of deserts, semideserts, and southern steppes of the northern hemisphere, where they include many Cruciferae and Papaveraceae. In the forest zone therophytes are represented mainly by field weeds, for example, cornflower, pennycress, and stork’s-bill.

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The high percentage of therophytes in the present study may be related to the seasonal rainfall (Galal and Fahmy, 2012).
On the other hand, life form spectrum of grasses showed that therophyte was the dominant one followed by hemi-cryptophytes and phanerophytes.
Geographic area Sites Species Medicinal species Eastern area 48 76 44 Western area 30 65 33 Middle area 1 10 1 Total 79 151 78 Table 6: Number of species in each life form for all species collected during the collection missions of Mediterranean coast of Libya during the spring and summer of 2009 and 2010 Life form Number of species % Trees 24 16 Phanerophyte (shrubs) 55 36 Chamaephyte (semi-shrubs) 11 7 Annual shrubs 4 3 Perennial forbs 24 16 Perennial grasses 17 11 Biennial forbs 2 1 Therophyte (annual forbs) 11 8 Climbers 3 2 Total 151 100 Table 7.
Nevertheless I prefer to include the Securigero-Dasypyrion in the Brometalia rubenti-tectorum (Chenopodietea) due to the occcurrence of significant anthropogenic component always associated with the Dasypyrum villosum grasslands; also the high number of the Helianthemetea mediterranean therophytes plays a supportive role.
La classification des types biologique prend en compte la position de bourgeon de renovation du vegetal par rapport au sol durant la periode froide est permet de reconnaitre 5 types biologiques, definis par Raunkiaer (1934) selon la nature morphologique et qui sont: phanerophyte, chamaephyte, hemicryptophyte, geophytes et therophytes.
The life form spectrum of the vascular flora indicates the predominance of therophytes (52%), with hemicryptophytes (15%) and phanerophytes (10%) (Figure 4).
The abundance of therophytes in comparison to other forms of life is important like the Algerian steppe [10], in the Moroccan wetland vegetation [20,21] and in the flora of Chott El Hodna in Algeria [72].
The proportions of herbaceous-subshrub/shrub-arboreal (epiphytes, succulents, chamaephytes, hemicryptophytes, and therophytes /phanerophytes) species were calculated for each of the vegetation types, for cerrado-caatinga transition, and for the different cerrado physiognomies.
Proposed by Raunkiaer (1934), the system classifies plants according to forms used to protect their perennating buds during unfavorable seasons, and groups them into five main classes: therophytes, cryptophytes, hemicryptophytes, chamaephytes and phanerophytes, according to their different resistance strategies to environmental conditions.
The percentage of megaphanerophytes, nanophanerophytes, Chameophytes, hemicryptophytes and therophytes were 18.
Therophytes predominate and the proportions of indigenous and introduced species are similar (Franceschi 1996).
Life form analysis of these two sites indicated the presence of therophytes (Th), chamaephytes (Ch), hemicryptophytes (H), geophytes (G) and phenerophytes (Ph).