Bromelioideae

Seeds of Bromelioideae reportedly lack appendages, and the outer integument simply degenerates to augment the gelatinous pulp that lls much of the often tough husk of the ripe berry (Smith and Downs 1974). Figure 3.6L illustrates some exceptions. Seeds in some cases possess unique qualities that seem likely to encourage transport or adhesion to substrates, perhaps in the second instance acting like the viscin threads of some mistletoes. Seeds of several ant-nest taxa promote myrmecochory with alluring chemicals (Chapters 6 and 8), and closer examination might reveal that some of the material attached to the seed constitutes tissue evolved to serve as ant food. Seeds of Bromelioideae (Ronnbergia) that disperse ballistically remain little studied. Self-fertile Ronn6ergia petersii germinates within the pear-shaped, orange (mammal-dispersed?) fruits that contain about 100 seeds, each enveloped in a gelatinous coat. Aechmea dactylina behaves similarly (Fig. 3.6B).

Authoritative sources (e.g., Smith and Downs 1979) describe Bromelioideae as baccate, which ts reality except for those few, relatively dry-fruited exceptions just mentioned. However, this designation conveys no information about the likely consequences of the diverse colors, sizes, textures and nutritional values of the berries most of these plants produce (Chapter 6; Table 6.7). Shape and seed number per fruit surely in uence appeal and access to vectors and substrates. For example, Madison (1979) suggested that size and form may help some species employ pupal mimicry to support ant-garden status (e.g., Aechmea mertensii). One at side on the seeds of certain epiphytes (Aechmea bracteata, Billbergia elegans; Fig. 3.6H) may promote sufficient contact with bark to counter gravity.

Aechmea magdalenae, a widespread terrestrial through Central America south to Ecuador, produces elliptical seeds that seem better suited to germinate on substrates other than bark (Fig. 3.6H).

Thick-walled sclerids forming the outer seed coat provide the protection the embryos and endosperm of zoochorous ora require (e.g., Billbergia elegans, B. rosea; Fig. 3.6I). Inner integuments consist of two layers of heavily scleri ed cells that vary enough among taxa to distinguish certain genera. Associated differences in hardness and resistance to corrosive gut secretions and grinding crops may reveal specializations for ingestion by mammals vs. avians.

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