Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Some Evolutionary Trends in the Bambusoideae (Poaceae)

Thomas R. Soderstrom
Annals of the Missouri Botanical Garden
Vol. 68, No. 1 (1981), pp. 15-47
DOI: 10.2307/2398809
Stable URL: http://www.jstor.org/stable/2398809
Page Count: 33
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Some Evolutionary Trends in the Bambusoideae (Poaceae)
Preview not available

Abstract

Bamboos, which have woody culms, and several genera with herbaceous culms share a similar type of leaf anatomy and epidermis. Various other morphological features, including a distinctive type of seedling, also indicate a close relationship that supports the grouping of these genera together into a single subfamily, the Bambusoideae. A review of the chromosome numbers in the subfamily reveals that the herbaceous members are mostly diploid while the woody ones are polyploid, with x = 12 the basic number. Such evidence corroborates the hypothesis that bamboos have been derived from herbaceous ancestors. Most bamboos flower infrequently and have had far less opportunity for floral evolution than have the herbaceous members, which flower continuously or at least seasonally. The most primitive inflorescences have therefore been retained in the bamboos while highly specialized ones have developed in the herbaceous members. A knowledge of the former type of inflorescence is useful in an interpretation of the latter. With this in mind, the inflorescence of the herbaceous bambusoid grass, Streptochaeta, has been reexamined. This genus has long been considered to be the most primitive grass, in great part due to the presence of three large structures in the spikelet, thought to be primitive lodicules and two structures interpreted as a primitive, two-parted palea. Comparison of Streptochaeta with other members of the Bambusoideae suggests that the spikelet in fact lacks both lodicules and palea and that these structures represent instead bracts on different axes of a highly modified pseudospikelet. Such a pseudospikelet is comparable to that of a bamboo. While Streptochaeta may be considered primitive in its herbaceous nature and possession of a pseudospikelet, it must be regarded as advanced in other features, among them the lack of lodicules. No one member of the subfamily can be considered most primitive. The least advanced inflorescences are retained in bamboos, such as Bambusa, while the most primitive growth form occurs in herbaceous genera like Streptochaeta, Streptogyna, and Pharus. The significant trends of evolution within the subfamily become apparent, however, only when all of the genera--woody and herbaceous--are considered together. The bambusoid line--with its complex leaf anatomy and epidermis--is itself specialized and not to be regarded as the precursor of the other groups of grasses.

Page Thumbnails

  • Thumbnail: Page 
[15]
    [15]
  • Thumbnail: Page 
16
    16
  • Thumbnail: Page 
17
    17
  • Thumbnail: Page 
18
    18
  • Thumbnail: Page 
19
    19
  • Thumbnail: Page 
20
    20
  • Thumbnail: Page 
21
    21
  • Thumbnail: Page 
22
    22
  • Thumbnail: Page 
23
    23
  • Thumbnail: Page 
24
    24
  • Thumbnail: Page 
25
    25
  • Thumbnail: Page 
26
    26
  • Thumbnail: Page 
27
    27
  • Thumbnail: Page 
28
    28
  • Thumbnail: Page 
29
    29
  • Thumbnail: Page 
30
    30
  • Thumbnail: Page 
31
    31
  • Thumbnail: Page 
32
    32
  • Thumbnail: Page 
33
    33
  • Thumbnail: Page 
34
    34
  • Thumbnail: Page 
35
    35
  • Thumbnail: Page 
36
    36
  • Thumbnail: Page 
37
    37
  • Thumbnail: Page 
38
    38
  • Thumbnail: Page 
39
    39
  • Thumbnail: Page 
40
    40
  • Thumbnail: Page 
41
    41
  • Thumbnail: Page 
42
    42
  • Thumbnail: Page 
43
    43
  • Thumbnail: Page 
44
    44
  • Thumbnail: Page 
45
    45
  • Thumbnail: Page 
46
    46
  • Thumbnail: Page 
47
    47