In this article we will discuss about:- 1. General Characters of Verbenaceae 2. Floral Formula of Verbenaceae 3. Number and Distribution 4. Range of Floral Structures 5. Common Plants 6. Affinity and Economic Importance.
General Characters of Verbenaceae:
Plants—herbs, shrubs or trees, often with square stems. Leaves —usually opposite or whorled, simple, sometimes pinnately or palmately compound (e.g., Vitex), exstipulate. Inflorescence—racemose or cymose, often with well-developed bracts. Flowers—usually zygomorphic, bisexual, hypogynous.
Sepals—(5), tubular or bell-shaped, persistent. Petals—(5), tubular, often oblique with a spreading limb, imbricate. Stamens—4, didynamous or 2, rarely 5 (e.g., Tectona), epipetalous. Carpels—(2), [but (4) in Durant); ovary superior, more or less lobed, often 2-4-celled with 2 or 1 ovule in each cell; style terminal. Fruit—usually drupaceous or of 4 nutlets (e.g., Verbena), rarely capsule (e.g., Avicennia). Seed—exalbuminous. Embryo— straight, with radicle turned downwards.
Floral Formula of Verbenaceae:
Number and Distribution of Verbenaceae:
This family consists of 80 genera and about 800 species belonging to the southern tropical and temperate regions.
Range of Floral Structures in Verbenaceae:
The flowers are usually pentamerous. The genus, Physopsis represents tetramerous flowers which exhibit a reduction in calyx. The tendency to zygomorphy is less marked in calyx than in the corolla, where an upper lip is formed by the union of the two upper lobes, as in Lantana, Lippia and others. The sepals show valvate aestivation and the petals, imbricate aestivation.
The 5-merous stamen is very rare, seems to be found in Tectona and Geunsia. The fifth stamen is generally represented by a staminode but it is usually obsolete. Stamens sometimes become diandrous which are formed by the reduction of staminodes of the two posterior or more rarely the two anterior stamens. The four stamens in some genera become fertile and equal.
The carpels are two in number and they are median, sometimes four carpels occur, as in Duranta, or five, as in Geunsia. In Lantana, Lippia and others the posterior carpel is abortive.
The ovary sometimes becomes rounded, but usually more or less lobed basing on the number of chambers. In Lantana the ovary is two-lobed but it is four-lobed in Clerodendron and Verbena.
Common Plants of Verbenaceae:
(1) Teak (Tectona grandis L. f.), an useful timber tree.
(2) Chaste-tree (Vitex negundo L.), a common shrub with trifoliate or quadrifoliate leaves.
(3) Clerodendron infortunatum Gaertn. = C. viscosum Vent, and C. inerme Gaertn., common herbs chiefly found on waste lands; C. siphonanthus R. Br.= C. indicum Ktze., a tall shrub about 6 ft. high with hollow stems.
(4) Petrea volubilis Jacq., a climber, very common in gardens.
(5) Duranta plumieri Jacq., a common hedge-plant with blue flowers and succulent yellow berries.
(6) Lantana indica Roxb. and L. camara L. = L. aculeata L. weeds chiefly found along roadsides.
(7) Lippia nodiflora Rich. = Phyla nodiflora Green, a herb commonly found in moist places, and L. geminata H. B. & Kunth., a shrub 3-8 ft. high.
(8) Verbain (Verbena officinalis L.), a small weed of waste places.
(9) Holmskioldia sanguinea Retz., a shrub commonly planted in gardens for the sake of its flowers.
(10) The white Mangrove (Avicennia officinalis L.), a common tree with long pneumatophores found in the salt-lakes near Calcutta and Sundribans, the seeds of which are viviparous.
(11) Gmelina arborea Roxb., a tree 60 ft. high.
(12) Gmelina hystrix Schult. = G. philippensis Cham., a garden plant.
(13) Premna integrifolia L., a shrub or small tree, chiefly found in the Sundribans.
(14) Callicarpa macrophylla Vahl., common on roadsides and village shrubberies.
(15) Callicarpa arborea Roxb., a tree about 40 ft. high.
(16) Congea tomentosa Roxb., a large climber.
(17) Aron’s rod (Stachytarpheta indica Vahl.), a herb 1-2 feet high.
Affinity and Economic Importance of Verbenaceae:
This family is closely allied to Acanthaceae and Labiatae but readily distinguished from the former by 2-4-celled ovary with 2 or 1 ovule in each cell and character of fruit, and from the latter by the form of the inflorescence and terminal style. It also establishes a link with Boraginaceae, but distinguished by the ascending ovule.
Economic Importance of Verbenaceae:
This family is perhaps most important economically. The leaves of Vitex are reputed as febrifuge. Clerodendron siphonanthus is a medicinal plant. Tectona grandis produces a useful timber. Some plants are ornamentals, such as, Clerodendron, Duranta, Holmskioldia, Lantana, Verbena, Vitex, Callicarpa, Petrea, Gmelina, Premna, etc.
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