Artocarpus Species Research Articles

Growth Rates and Population Structure of Moraceae Trees in Sarawak, East Malaysia

To understand the relationship between the dynamics of tropical rain forests and the population processes of individual species, data are needed on the rates at which trees grow, die, and establish. Data on the family Moraceae have been extracted from long—term forestry studies in Sarawak, on the northwest coast of Borneo, an area at the center of species richness of Old World tropical forests. These data can also be combined with forest maps and logging studies to investigate the importance of competition and disturbance in controlling tree growth. Tree populations of Moraceae species had mean annual diameter increments of between 0.4 and 3 mm/yr. Growth rates increased two to six times in the 1st and 2nd yr following (selective) logging, but began to decline somewhat in the 3rd and 4th yr. Growth rate variation among trees in a population was considerable, with most trees showing little or no growth, and a few, high growth rates. Saplings of Artocarpus species increased in diameter at the same mean rate as adult trees. Annual mortality rates were low in primary forest, typically <3%, and indicated stable populations. In logged forest, annual mortality of Artocarpus species was considerably higher, between 5 and 8% for trees and still higher for saplings. Adults and saplings of Ficus, a pioneer species, had much higher annual mortality rates than individuals of Artocarpus. Growth rates of Moraceae trees in primary forest were positively correlated with the growth of the nearest conspecific trees, the mean growth rates of the three nearest neighbors of any species, and the mean distance to the nearest neighbors, but were not correlated with the diameter of the tree itself and the mean diameter of the three nearest neighbors. Analysis of patches of three trees of any species in primary forest revealed that there were no detectable differences among patches in either tree size or growth rate. Tree growth rates of small patches in logged forest were negatively correlated with distance to the nearest forest opening. Even the significant relationships between tree growth rate and immediate neighborhood explained only a relatively small portion of the total variation in growth rate. The remaining variation may be due to variation in plant genotype and local environment.

Morphological and anatomical investigations onArtocarpus forst

1. The morphological and anatomical features of seven species ofArtocarpus have been studied and described at some length.

The Leaf-Base and the Interdone- Their true Morphology


 Development of the leaf primordium at the shoot apices of 14 species of dicotyledons has been studied.
 These include exstipulate, stipulate and sheathing leaves with or without a free base.
 The axial component which is laid down first during the initiation of a leaf development at the apex of a vegetative shoot is a part of the leaf and is to be considered as its base.
 In species where a free base is wanting, the axial component represents the only base and the cauline and discontinuous stipular scar, which led Ponzo, Cross and others to doubt the origin of stipules from the leaf-base, is explained.
 The development of a free base in the form of a sheath and/or a pair of stipules depends on the course and behaviour of the trace bundles through the axial component (e.g. in species of Centella, Polygonum, Ixora, Ervatamia, Rosa, Morus, Calotropis, Artocarpus, Ficus, Paederia, Hibiscus and Pisum).
 If the laterals change their vertical course, bend and follow an oblique horizontal course towards the median at the top of the axial component, the petiole appears to be inserted directly on the axis without any evident base (free) as in the species of Ficus, Paederia, Jasminum, Hibiscus, Morus and Pisum
 If during the horizontal course the laterals branch in the axial component, a single (Ficus elastica, Ervatamia divaricata, Polygonum orientale), or a pair of stipules (Ficus religiosa, Artocarpus integrifolia, Morus alba, Hibiscus rosa-sinensis, Pisum sativum and Rosa centifolia), or a composite stipule (Ixora parviflora and Paederia foetida), are formed with the branches as their traces, and the stipular scars appear cauline.
 If the laterals, two or many, run almost parallel to one another and to the median, even after leaving the axial component for some time before they turn towards the median, a sheathing but free base is formed which partially or completely encloses the axis, depending on the number and nature of the course of the laterals (e.g. Centella and Rosa).
 If in a multilacunar node the laterals branch during their horizontal course towards the median the stipule formed is either an ochrea (Polygonum), or bud scales (species of Ficus and Artocarpus).
 If, however, the laterals do not branch and gradually shift towards the median where they form with the latter a ring of vascular bundles, the sheath becomes oblique and tapering without any stipule (Centella).
 The base, i.e. the axial component, and its free portion, if there be any, can be anatomically distinguished by the nature and behaviour of the laterals, from the petiole: in the base they gradually approach the median without joining it and may branch, but in petiole they either join with the median (Rosa) or arrange themselves with the latter in the form of a ring of vascular bundles (Centella). They again branch in connection with leaflet and lamina formation.
 The internode is made up of an axial core and a mantle derived from two different zones of the eumeristem - the corpus and the flank meristems. The mantle is made by base or bases (axial component or components) of the leaves, and extends radially up to the pith as suggested by Hofmeister.

Fossil Plants as Tests of Climate

IN continuation of my recent letter, permit me to call attention to a communication on the bread fruit trees in North America, by Mr. F. H. Knowlton, of the National Museum, Washington, U.S., which appears in your American contemporary Science for January 13. The forty living species of Artocarpus are all confined to tropical Asia and the Malay Archipelago. A. incisa, the true bread fruit tree, and one or two others, are largely cultivated in the tropics. They are small or medium-sized trees with a milky juice, large leathery leaves, and monœcious flowers. The female flowers are long club-shaped spikes, which uniting form one large mass known as the “bread fruit,” the interior containing a pulp when ripe like new bread.