Marx makes use of trees in The Trinity Formula in the same manner as I pointed out in yesterday’s post:
Whatever may be the disparity of these relations in other respects, they all have this in common: Capital yields a profit year after year to the capitalist, land a ground-rent to the landlord, and labour-power, under normal conditions and so long as it remains useful labour-power, a wage to the labourer. These three portions of total value annually produced, and the corresponding portions of the annually created total product (leaving aside for the present any consideration of accumulation), may be annually consumed by their respective owners, without exhausting the source of their reproduction. They are like the annually consumable fruits of a perennial tree, or rather three trees; they form the annual incomes of three classes, capitalist, landowner and labourer, revenues distributed by the functioning capitalist in his capacity as direct extorter of surplus-labour and employer of labour in general. Thus, capital appears to the capitalist, land to the landlord, and labour-power, or rather labour itself, to the labourer (since he actually sells labour-power only as it is manifested, and since the price of labour-power, as previously shown, inevitably appears as the price of labour under the capitalist mode of production), as three different sources of their specific revenues, namely, profit, ground-rent and wages. They are really so in the sense that capital is a perennial pumping-machine of surplus-labour for the capitalist, land a perennial magnet for the landlord, attracting a portion of the surplus-value pumped out by capital, and finally, labour the constantly self-renewing condition and ever self-renewing means of acquiring under the title of wages a portion of the value created by the labourer and thus a part of the social product measured by this portion of value, i.e., the necessities of life. They are so, furthermore, in the sense that capital fixes a portion of the value and thereby of the product of the annual labour in the form of profit; landed property fixes another portion in the form of rent; and wage-labour fixes a third portion in the form of wages, and precisely by this transformation converts them into revenues of the capitalist, landowner, and labourer, without, however, creating the substance itself which is transformed into these various categories. The distribution rather presupposes the existence of this substance, namely, the total value of the annual product, which is nothing but materialised social labour. Nevertheless, it is not in this form that the matter appears to the agents of production, the bearers of the various functions in the production process, but rather in a distorted form. Why this takes place will be developed in the further course of our analysis. Capital landed property and labour appear to those agents of production as three different, independent sources, from which as such there arise three different components of the annually produced value — and thereby the product in which it exists; thus, from which there arise not merely the different forms of this value as revenues falling to the share of particular factors in the social process of production, but from which this value itself arises, and thereby the substance of these forms of revenue.