Pollen grains and massulae in pollinia of four South American palustrine species of Habenaria (Orchidaceae)

Figures & data

Figure 1. Pollinium and massulae in Habenaria species. A. Pollinium of H. gourlieana; B. Loose massulae from a pollinium of H. paucifolia; C, D. Massulae of H. secunda: C. Radially arranged, triangular in outline massulae; D. Loose massulae. E, F. Massulae of H. bractescens: E. Part o a pollinium with a group of tabular massulae and elastoviscin threads; F. An isolated, tabular, oblong in outline massula. Scale bars – 0.35 mm (A); 110 μm (B, C); 70 μm (D, E); 30 μm (F).

Figure 4. Wall structure in Habenaria gourlieana. A, C. LM & B, D–F. TEM. A. Quadrangular external tetrad. B. Inner grains with exine without reticulum, and wide intine. C. Tetragonal and other types of tetrads. D. Pollen wall (detail), partial muri and pila with pollenkit inside and over. E. External grains of tetrads with reticulum-like exine, pollenkit present among baculae. F. Detail of wall in internal pollen grains with intine and granular exine. Scale bars – 10 μm (A, C); 5 μm (B, E); 0.5 μm (D, F).

Figure 2. Details of massulae and elastoviscine threads in Habenaria species. A–C. Ramified elastoviscin, apparently hollow threads in: A. H. paucifolia; B. H. bractescens (elastoviscin threads showing pores); C. H. secunda. D. Massula of H. gourlieana, viscous elastoviscin threads and pollenkit-like substance on massulae. Scale bars – 5 μm (A–D).

Figure 3. Types of walls in Habenaria species. A. Reticulum with rounded, thin, continuous muri of H. bractescens, and elastoviscin thread with pores. B, C. Coarse, thick muri in: B. H. paucifolia; C. H. secunda. D. Interrupted, broken, discontinuous muri, with granules over them, and isolated elements, possible pila in H. gourlieana. Scale bars – 3 μm.

Table I. Comparison of floral and palynological characters of species of Habenaria.

Characters	H. bractescens	H. gourlieana	H. paucifolia	H. secunda
Size of spur, mm	60 (medium)	100 (large)	14 (small)	7 (small)
Size of labellum, mm	10	16	7.5	8
Size of sepals, mm	17	40	7	7
Massulae shape	Tabular	Piriform	Piriform	Piriform
Massulae outline	Oblong	Triangular	Triangular	Triangular
Massulae size, mm	0.20 ± 0.004	0.35 ± 0.002	0.15 ± 0.007	0.25 ± 0.005
Ornamentation of pollen grains	Reticulate	Discontinuously reticulate	Reticulate	Reticulate
Muri or pila width, μm	2.9 ± 0.2	2.9 ± 0.5	5 ± 0.9	6.4 ± 1.2
Threads	Branched, with pores	Simple, without pores	Branched, without pores	Simple, without pores